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DISSECTION  METHODS 
AND  GUIDES 


BY 

DAVID  GREGG  METHENY 

M.  D.,  L.  R.  C.  P.,  L.  R.  C.  S.  (Edin.),  L.  F.  P.  S.  (Glas.) 

ASSOCIATE  IN  ANATOMY,   AND   FOR   SOMETIME  SENIOR    DEMONSTRATOR    IN    THE 

DANIEL  BAUGH  INSTITUTE,  THE  DEPARTMENT    OF    ANATOMY  AND  BIOLOGY,  JEP- 

FERSON  MEDICAL  COLLEGE,  PHILADELPHIA 


ILLUSTRATED 


PHILADELPHIA    AND    LONDON 


W.   B.   SAUNDERS    COMPANY 

1914 


Copyright,  1914,  by  W.  B.  Saunders  Company 


PRINTED    IN    AMERICA 

PRESS    OF 

W.    B.    SAUNDERS    COMPANY 

PHILADELPHIA 


TO 

3f.  SuIanJi  Mljttate.  1.  A.,  M,  1.  (Slnttintt) 

FELLOW  OF   THE   ROYAL  COLLEGE  OF   PHYSICIANS,   EDINBURGH 
LECTURER   ON  ANATOMY,   SURGEON'S  HALL,   EDINBUKGH 

This  small  Manual 
is  affectionately  and  respectfully 

by  one  of  his  former  Pupils,  the  Author 


6'i5i 


INTRODUCTION 

This  book  is  intended  to  bridge  the  gap  that  exists 
between  the  descriptive  text-book  and  the  dissecting 
table.  It  is  designed  for  use  in  conjunction  with  a 
text-book,  but  it  is  not  to  supplant  it  in  any  way.  In 
order  that  it  may  be  used  in  connection  with  any 
text-book  or  atlas,  both  the  old  and  the  new  anatomical 
names  have  been  given.  If  the  instructions  seem  to  be 
too  minute,  it  should  be  remembered  that  the  student's 
first  effort  may  happen  to  be  that  very  dissection; 
therefore  nothing  has  been  left  to  chance.  Every- 
thing that  a  student  could  reasonably  be  expected  to 
do  in  any  well-equipped  dissecting  room  has  been 
carefully  explained.  Some  of  the  dissections  are  orig- 
inal, and  all  of  them  have  been  carefully  selected  with 
a  view  to  their  being  well  within  the  capacity  of  the 
average  student  to  perform. 

The  real  ability  of  a  practising  physician  or  surgeon 
must  often  depend  on  a  true  knowledge  of  human 
anatomy. 

Anatomy  that  has  merely  been  memorized  can  only 
be  of  service  in  passing  examinations.  Such  anatomy 
is  speedily  forgotten,  and  can  never  be  of  any  real 
value. 


6  INTRODUCTION 

To  be  of  real  service,  anatomy  must  be  remembered 
not  only  by  the  mind,  but  also  by  the  eye  and  the  hand. 
Therefore  the  eye,  hand,  and  mind  should  simul- 
taneously be  trained  in  the  recognition  of  the  appear- 
ance, shape,  texture,  relative  size,  relative  position, 
and  the  other  peculiarities  of  the  many  various  struc- 
tures of  the  human  body.  Some  of  this  can  be  learned 
at  bedside  and  operating  table,  but  it  all  should  have 
been  thoroughly  learned  long  before  that,  and  it  can 
be  thoroughly  learned  only  in  the  dissecting  room. 
The  great  majority  of  students  find  in  the  dissecting 
room  their  only  opportunity  of  gaining  that  mastery 
of  anatomy  which  will  make  it  their  servant  in  after 
life;  therefore  it  cannot  be  too  strongly  urged  that  the 
entire  body  be  dissected  conscientiously  and  thor- 
oughly. 

Whatever  else  the  student  may  gain,  the  main 
object  in  doing  a  dissection  is  to  so  prepare  a  region 
that  its  component  structures  may  be  studied  to  ad- 
vantage. It  is  the  dissection,  rather  than  the  book, 
that  should  be  studied. 

Mutilation  teaches  nothing  and  ruins  a  region  for 
subsequent  study,  while  a  dissection  in  which  the 
structures  have  been  carefully  cleaned  and  preserved 
may  be  of  vast  service. 

A  dissection,  therefore,  should  be  in  the  best  possible 
condition  for  study.  The  student  may  never  have 
another  such   opportunity.     It  is  not  reasonable   to 


INTRODUCTION  7 

expect  a  tyro  to  show  the  judgment  of  an  expert  in 
planning  a  dissection,  and  the  unguided  effort  may  be 
disastrous.  Surely  it  is  safer  not  to  leave  too  much  to 
chance,  and,  still  better,  to  make  sure  that  the  student 
will  have  a  good,  clean  dissection.  This  book  has  been 
written  in  the  hope  that  it  may  help  and  encourage 
the  student  in  the  making  of  good,  clean  dissections 
which  will  show  all  of  the  important  structures  without 
ruining  the  part  for  subsequent  work. 

D.  G.  Metheny. 

4609  Spruce  St.,  Philadelphia,  Pa., 
November,  1914. 


CONTENTS 


PAGE 

CONCERNING  EQUIPMENT 11 

METHODS  OF  DISSECTING 12 

HEAD  AND  NECK 16 

Back  Part  of  the  Scalp 16 

Superficial  Dissection  of  the  Back  of  the  Neck 19 

Suboccipital  Triangle 20 

Front  Part  of  Scalp 21 

Posterior  Triangle  of  the  Neck,  Superficial  Dissection 22 

Posterior  Triangle  of  the  Neck,  Deep  Dissection 25 

Anterior  Triangle  of  the  Neck,  Lower  Part 26 

Subclavian  Triangle 28 

Anterior  Triangle  of  the  Neck,  Upper  Part 29 

The  Region  of  the  Face 32 

Removal  of  the  Brain 34 

Orbit  and  Eye 36 

Sphenopalatine  Fossa  and  Internal  Maxillary  Artery 39 

Pharynx 41 

Prevertebral  Region 43 

Soft  Palate 43 

Nasopharynx 45 

Tongue 45 

Larynx 47 

THORAX  AND  ABDOMEN 49 

Ischiorectal  Fossa 49 

Perineum  Proper  (Male) 52 

Perineum  Proper  (Female) 54 

Thorax  and  Its  Contents 56 

Abdominal  Wall  and  Inguinal  Hernia 64 

Inguinal  and  Femoral  Hernia  from  Behind 66 

Abdominal  Contents 68 

Pelvic  Contents  in  General 72 

Pelvic  Viscera  (Male) 74 

Pelvic  Viscera  (Female) 75 

Pelvic  Contents  in  General  (Concluded) 75 

Spermatic  Cord  and  Testicle 76 

9 


10  CONTENTS 

PAGE 

Penis  and  Male  Urethra 77 

The  Muscles  of  the  Back 78 

Spinal  Cord 79 

UPPER  EXTREMITY 82 

Trapezius  and  Latissimus  Dorsi 82 

Shoulder 84 

The  Pectoral  Muscles  and  Axilla 86 

The  Arm 89 

Dismemberment 90 

Forearm,  Superficial  Dissection 91 

Back  of  the  Forearm  and  Hand 94 

Palm  of  the  Hand,  Superficial  Dissection 96 

Front  of  the  Forearm,  Deep  Dissection 100 

The  Hand,  Deep  Dissection 103 

LOWER  EXTREMITY 105 

Gluteal  Region 105 

Back  of  Thigh 110 

Popliteal  Space 112 

Back  of  Leg,  Deep  Dissection 114 

The  Sole  of  the  Foot 116 

Front  of  Thigh,  Superficial  Dissection 121 

Deep  Dissection  of  the  Front  and  Inner  Side  op  the  Thigh  .  .  124 

Front  of  the  Leg  and  Dorsum  of  Foot 127 


DISSECTION  METHODS  AND  GUIDES 


CONCERNING  EQUIPMENT 

Although  every  well-equipped  anatomical  labora- 
tory supplies  its  students  with  much  of  the  requisite 
paraphernalia,  there  are  still  some  things  which  the 
student  should  personally  possess.  It  is  very  diffi- 
cult to  do  good  work  without  an  adequate  equipment. 
The  small  toy-like  instruments  to  be  found  in  the 
average  "pocket  dissecting  case"  are,  almost  all  of  them, 
valueless  for  dissecting  purposes.  They  are  seldom 
of  the  right  size  or  shape,  and  they  usually  are  miser- 
ably constructed  from  the  very  cheapest  and  poor- 
est quality  of  material.  The  student  had  better  not 
waste  any  money  on  the  usual  run  of  pocket  cases. 
Anyway,  a  pocket  is  no  place  for  a  dissecting  room 
outfit. 

The  student  should  have  at  least  the  following 
articles : 

One  spool  of  strong  white  linen  thread. 

Several  curved  needles,  both  large  and  small. 

One  dozen  bead-headed  steel  pins,  or  ''Moore  push 
pins." 

One  Maw's  dissector,  or  a  strong  bent  ''blunt  probe," 
such  as  is  used  by  dentists  for  plastic  filling. 

One  pair  of  rat-toothed  tissue  forceps. 

11 


12  DISSECTION  METHODS  AND  GUIDES 

Two  pairs  of  dissecting  forceps.  Forceps  should 
be  about  6  inches  long  and  have  a  very  ''soft"  spring. 

One  pair  of  blunt-pointed  curved  scissors.  The 
scissors  should  be  at  least  6  inches  long,  both  blades 
should  be  abruptly  blunt,  ''curved  on  the  flat,"  and 
have  a  screw  lock. 

One  set  of  chain  hooks,  which  should  be  very  sharp 
pointed. 

One  small  bladed  scalpel. 

Two  large  bladed  scalpels. 

Scalpels  should  have  large  flat  handles.  The 
"English  model"  of  blade  is  by  far  the  most  conven- 
ient, the  "French  model"  is  next  best.  All  of  these 
should  be  of  the  very  finest  quality  that  can  be  had, 
anything  less  will,  in  the  long  run,  prove  very  disap- 
pointing. 


METHODS  OF  DISSECTING 

The  Skin. — It  is  always  desirable  that  skin-flaps 
be  kept  as  large  as  possible,  so  that  they  can  be  used 
in  covering  up  a  dissection  to  keep  it  from  drying 
out. 

Never  make  any  skin  incision  when  it  can  be  avoided, 
especially  a  transverse  incision. 

Fat. — As  a  general  rule  the  superficial  fat  should 
not  be  removed  along  with  the  skin.  Any  important 
structures  embedded  in  the  fat  should  be  isolated  and 
lifted  up  out  of  the  way  of  injury  before  attempting 
to  remove  the  fat.  All  fat  should  be  thoroughly  re- 
moved as  soon  as  there  is  no  danger  of  injuring  im- 
portant structures.    One  of  the  most  satisfactory  ways 


METHODS  OF  DISSECTING  13 

of  speedily  removing  fat  is  to  trim  it  away  with  the 
convex  side  of  a  pair  of  curved  scissors. 

Areolar  Tissue. — All  loose  areolar  tissue  should  be 
promptly  removed.  When  it  covers  in  some  im- 
portant structure  and  happens  to  be  dense,  it  should 
be  picked  up  between  two  pairs  of  forceps  and  torn 
apart. 

The  student  should  hasten  to  acquire  this  method 
of  ''dissecting  between  two  forceps"  because  it  is  a 
very  rapid  as  well  as  a  s^fe  way  of  working.  The 
areolar  tissue  is  often  condensed  into  a  sort  of  sheath 
for  blood-vessels  and  nerves  passing  through  it.  In 
all  cases  the  important  structures  should  be  traced 
out  and  freed  before  any  attempt  is  made  to  remove 
the  areolar  tissue  and  fat  by  which  they  may  be  sur- 
rounded. As  soon  as  you  have  made  sure  that  the 
important  vessels  and  nerves  are  safe  from  injury, 
remove  all  areolar  tissue  and  fat. 

Never  allow  it  to  remain  over  night,  because  if  it 
should  become  dry  its  removal  becomes  very  tedious, 
if  not  impossible. 

Muscles. — Never  use  great  force  in  moving  the 
arms  or  legs  of  a  body,  nor  in  forcing  the  body  itself 
into  any  unusual  attitude,  especially  if  it  is  very  rigid 
or  frozen,  because  in  these  conditions  the  muscles 
are  almost  sure  to  be  badly  torn.  It  is  far  better  to 
divide  an  unyielding  muscle  than  to  tear  it  in  two. 
But  no  muscle  should  ever  be  divided  at  any  other 
time  unless  it  is  one  that  cannot  be  retracted  out  of 
the  way.  All  muscles  should  be  freed,  as  much  as 
possible,  from  adjoining  structures.  The  best  way  of 
freeing   muscles  from  each  other  is  to  use  a  finger. 


14  DISSECTION  METHODS  AND  GUIDES 

All  loose  areolar  tissue  and  fat  should  be  removed 
from  between  muscles  as  soon  as  it  can  be  done  with- 
out danger  of  injuring  important  vessels  and  nerves. 
When  the  sheath  of  a  muscle  is  very  dense  and  thick 
it  should  be  entirely  removed.  An  easy  way  of  doing 
this  is  to  snip  it  free  with  the  blunt  points  of  your 
scissors,  working  always  in  the  direction  of  the  muscle- 
fibers. 

If  the  intervals  between  muscles  are  indistinct  or 
indistinguishable  on  account  of  the  density  of  the 
overlying  fascia,  as  in  the  front  of  the  leg,  then  com- 
mence by  separating  their  tendons  and  working  back 
to  the  muscles  themselves. 

Arteries. — All  important  arteries  should  be  thor- 
oughly cleaned  and  all  venae  comites  should  be  removed. 
The  sheaths  of  large  arteries  should  always  be  re- 
moved with  blunt-pointed  scissors,  never  with  a  knife. 
In  cleaning  a  large  artery,  rip  the  sheath  lengthwise  for 
a  short  distance,  seize  it  between  two  pairs  of  forceps, 
and  tear  it  open  along  the  line  of  the  artery.  When 
it  is  too  tough  to  tear  readily,  snip  it  with  blunt- 
pointed  scissors.  In  this  way  it  is  always  easy  to  see 
branches  long  before  they  are  in  danger  of  division. 
When  you  encounter  a  branch,  divide  the  main  sheath 
transversely  at  the  base  of  the  branch,  then  trim  it 
around  the  branch. 

The  sheath  of  a  small  artery  is  easily  removed  by 
ripping  it  along  the  line  of  the  vessel  with  a  dentist's 
blunt-pointed  bent  probe,  or  by  tearing  it  between 
two  forceps;  only  an  occasional  snip  with  scissors 
will  be  necessary.  As  soon  as  it  can  be  done  without 
danger  to  adjacent  vessels  or  nerves,  the  sheath  of  a 


METHODS  OF  DISSECTING  15 

vessel  should  always  be  removed.  It  should  never  be 
given  an  opportunity  to  roll  itself  up  into  a  pseudo- 
nerve.  The  same  injunction  applies  to  all  long  strands 
of  fascia. 

Veins. — These  are  to  be  cleaned  in  exactly  the  same 
way  as  arteries,  except  that  they  require  more  care 
on  account  of  their  being  thin-walled  and  easily  torn. 
Only  the  larger  veins  need  be  saved;  the  smaller 
ones  would  interfere  too  much  with  subsequent  dis- 
section, so  they  must  be  sacrificed.  It  is  always  best 
to  tie  a  vein  before  cutting  it  away,  otherwise  it  is 
almost  sure  to  cause  much  annoyance  by  leaking.  If 
a  large  vein  be  torn  laterally,  tie  it  both  above  and 
below  the  tear. 

Nerves. — These  should  be  cleaned  with  the  same 
scrupulous  care  that  is  bestowed  on  blood-vessels. 
However,  they  are  never  so  closely  invested  and  are 
much  easier  to  clean.  Whenever  any  important  vessel 
or  nerve  has  been  accidentally  divided,  always  tie  it 
together  again  before  you  have  time  to  forget  about 
it. 

Always  keep  your  dissection  and  its  surroundings 
as  scrupulously  clean  as  possible;  it  will  tend  to  make 
your  work  pleasant  as  well  as  interesting.  Always  have 
at  hand  a  good  atlas  or  text-book.  Lastly,  remember 
that  all  of  these  directions  and  instructions  are  vastly 
more  grievous  to  read  than  they  are  to  fulfil. 


HEAD  AND  NECK 

Order  of  Dissections 

1.  Back  part  of  the  Scalp. 

2.  Back  of  the  Neck. 

3.  Suboccipital  Triangle. 

4.  Front  part  of  Scalp. 

5.  Posterior  Triangle  of  the  Neck,  superficial  dissection. 

6.  Posterior  Triangle  of  the  Neck,  deep  dissection. 

7.  Anterior  Triangle,  superficial  dissection. 

8.  Subclavian  Triangle. 

9.  Carotid  Triangles,  deep  dissection. 

10.  Anterior  Triangle,  deep  dissection  of  Upper  Part. 

11.  Face. 

12.  Removal  of  Calva  and  Brain. 

13.  Orbit  from  above. 

14.  Orbit  from  the  outer  side. 

15.  Sphenopalatine  Fossa. 

16.  Pharynx. 

17.  Transverse  section  of  Skull  and  Prevertebral  Region. 

18.  Soft  Palate. 

19.  Sagittal  section  of  Skull.     Nasopharjrnx. 

20.  Tongue. 

21.  Larynx. 

BACK  PART  OF  THE   SCALP 

From  a  point  slightly  above  one  ear,  make  an  in- 
cision across  the  top  of  the  head  to  the  corresponding 
point  above  the  other  ear.     From  the  middle  of  this 

16 


BACK  PART  OF  THE  SCALP 


17 


Fig.  1. — Back  op  Head  and  Neck. 

Knife  incisions  are  shown  by  continuous  red  lines.     Dotted  red  lines  show 

where  the  skin  is  to  be  cut  with  scissors. 


18  DISSECTION  METHODS  AND  GUIDES 

incision,  make  another  incision  down  the  midline  of 
the  back  of  the  head  and  neck,  as  far  down  as  the 
spine  of  the  first  thoracic  vertebra.  Begin  at  the 
very  top  and  reflect  the  skin  downwards  until  you 
reach  the  level  of  the  ear,  then  begin  in  the  midline 
incision  and  reflect  the  skin  forwards  and  outwards 
as  far  as  the  line  joining  the  lobe  of  the  ear  to  the 
point  of  the  acromion  process.  Just  back  of  the 
ear,  look  for  the  Posterior  Auricular  Artery  (a.  auricu- 
laris  posterior)  and  Posterior  Auricular  Vein  (v.  auricu- 
laris  posterior).  Pick  up  these  vessels  and  clean  them 
from  below  upwards.  Just  back  of  the  mastoid  process 
you  will  find  the  Small  Occipital  Nerve  (n.  occipitalis 
minor)  and  the  Occipital  Artery  {a.  occipitalis)  emerg- 
ing from  the  deep  fascia,  just  back  of  the  Sterno- 
mastoid  Muscle  (m.  sternocleidomastoideus) .  The  nerve 
lies  nearer  the  posterior  edge  of  the  Stemomastoid 
(m.  sternocleidomastoideus)  than  does  the  artery,  and 
as  it  is  superficial  to  the  artery  it  should  be  cleaned 
first,  working  from  below  upwards. 

The  Occipital  Artery  (a.  occipitalis)  lies  somewhat 
posterior  to  the  Small  Occipital  Nerve  {n.  occipitalis 
minor)  and  it  is  more  deeply  embedded.  Follow  the 
Occipital  Artery  (a.  occipitalis)  backwards  until  you 
encounter  the  Great  Occipital  Nerve  (n.  occipitalis 
major)  and  Occipital  Vein  (v.  occipitalis)  where  they 
cross  it.  The  Occipital  Vein  (v.  occipitalis)  pierces 
the  deep  fascia  just  external  to  the  occipital  attach- 
ment of  the  Trapezius  Muscle.  Clean  the  Occipital 
Vein  (v.  occipitalis),  working  from  below  upwards. 

The  Great  Occipital  Nerve  (n.  occipitalis  major) 
pierces  the  outer  edge  of  the  Trapezius  Muscle  close 


SUPERFICIAL  DISSECTION  OF  THE  BACK  OF  THE  NECK     19 

to  its  occipital  attachment,  and  can  readily  be  found 
by  lifting  up  the  outer  edge  of  the  Trapezius  and  ex- 
posing it  as  it  emerges  from  the  Complexus  Muscle 
(m.  semispinalis  capitis),  just  before  piercing  the  Trap- 
ezius. Clean  the  Great  Occipital  Nerve  {n.  occipitalis 
major),  working  from  below  upwards.  Both  the  Occip- 
ital Vein  (y.  occipitalis)  and  the  Great  Occipital  Nerve 
(n.  occipitalis  major)  are  superficial  to  the  Occipital 
Artery  (a.  occipitalis)  and  should  serve  as  a  guide  to  it. 
Clean  the  superficial  portion  of  the  Occipital  Artery  (a. 
occipitalis),  working  from  below  upwards.  All  the  fore- 
going vessels  and  nerves  being  well  cleaned,  it  will  now 
be  possible  to  lift  them  up  or  to  retract  them,  so  as  to 
permit  a  speedy  and  complete  removal  of  all  of  the  fat 
overlying  the  posterior  belly  of  the  Occipitofrontalis 
Muscle  (m.  epicranius).  The  Occipitalis  Muscle  (m. 
epicranius)  should  be  cleaned  by  removal  of  all  the 
overlying  fat,  which  can  most  easily  be  done  by  using 
a  pair  of  scissors  ^'curved  on  the  flat." 

SUPERFICIAL  DISSECTION   OF  THE  BACK  OF  THE  NECK 

Thoroughly  clean  the  cervical  portion  of  both  Trap- 
ezii  Muscles,  working  from  above  downwards  and 
outwards.  Be  especially  careful  not  to  tear  or  injure 
the  thin,  free,  antero-external  borders  of  these  muscles. 
The  Right  Trapezius  should  now  be  divided  transversely 
along  its  attachment  to  the  acromion  process  and 
spine  of  the  scapula,  but  do  not  divide  its  clavicular 
attachment.  Retain  its  occipital  attachment,  but 
divide  its  vertebral  attachment  about  1  inch  from  the 
midline.  In  doing  this  be  careful  not  to  cut  the  mus- 
cles which  are  attached  to  the  vertebral  border  of  the 


20  DISSECTION  METHODS  AND  GUIDES 

scapula.  It  will  be  well  to  use  scissors  in  severing 
the  vertebral  attachment  of  the  Trapezius.  Do  so 
gradually  while  freeing  the  Trapezius,  with  your 
fingers,  from  the  underlying  muscles,  always  in  ad- 
vance of  your  scissors.  Reflect  the  Right  Trapezius 
outwards. 

The  Left  Trapezius  should  now  be  divided  trans- 
versely, as  was  the  right,  but  its  clavicular  attach- 
ment is  to  be  severed  as  well. 

It  should  be  reflected  backwards  toward  the  mid- 
line, but  it  should  not  be  detached  from  the  vertebrae 
or  occiput.  Clean  the  Splenius  Capitis  Muscle  on 
each  side.  Clean  the  easily  accessible  portion  of  the 
Princeps  Cervicis  {ramus  descencens)  branch  of  the 
Occipital  Artery  (a.  occipitalis).  Be  careful  not  to 
cut  the  Lesser  Occipital  Nerve  {n.  occipitalis  minor) 
lying  close  to  the  posterior  border  of  the  Stemo- 
mastoid  Muscle  (w.  sternocleidomastoideus) .  It  should 
not  be  molested  at  this  stage.  Clean  the  entire  Levator 
AnguU  Scapulae  (w.  levator  scapulos)  and  then  the 
upper  part  of  the  Complexus  Muscle  (m.  semispinalis 
capitis) . 

SUBOCCIPITAL  TRIANGLE 

On  the  Left  side  only,  remove  entirely  the  Splenius 
Capitis  Muscle,  divide  the  Levator  Anguli  Scapulae  (m. 
levator  scapulce),  reflect  the  lower  half  downwards,  and 
entirely  remove  the  upper  half.  Now  remove  the  Com- 
plexus (w.  semispinalis  capitis)  and  thoroughly  clean 
the  Tracheolomastoid  Muscle  (m.  longissimus  capitis). 

Locate  the  spinous  process  of  the  Axis  (second  cervi- 
cal vertebra),  then  with  scissors,  ''curved  on  the  flat," 
remove  all  the  overlying  fat.    You  should  now  readily 


FRONT  PART  OF  SCALP  21 

locate  the  transverse  process  of  the  Atlas  (first  cervical 
vertebra).  Now  clean  the  following  muscles  in  exactly 
the  following  order: 

First,  the  Superior  ObUque  (m.  obliquus  capitis 
superior);  second,  the  Inferior  ObUque  (m.  obliquus 
capitis  inferior);  third,  the  Rectus  Capitis  Posticus 
Major  (m.  rectus  capitis  posterior  major);  fourth,  the 
Rectus  Capitis  Posticus  Minor  (m.  rectus  capitis  poste- 
rior minor). 

You  should  be  able  to  find  the  Vertebral  Artery 
(a.  vertebralis)  in  the  triangular  interval  formed  by 
the  Superior  Oblique  (w.  obliquus  capitis  superior) 
above,  the  Inferior  ObUque  (m.  obliquus  capitis  infe- 
rior) below,  and  the  outer  edge  of  the  Rectus  Capitis 
Posticus  Major  (m.  rectus  capitis  posterior  major). 
It  will  be  necessary  to  defer  dissecting  the  preverte- 
bral muscles  of  the  head  and  neck  until  after  the 
pharynx  has  been  dissected. 

FRONT  PART  OF  SCALP 

Make  a  longitudinal  incision  in  the  midUne,  begin- 
ning at  the  vertex  of  the  skull  and  ending  at  the  root 
of  the  Nose  (or  Nasion,  in  the  middle  of  the  naso- 
frontal groove).  Reflect  the  skin  downwards  as  far 
as  the  level  of  the  eyebrow.  Do  not  attempt  to  remove 
any  of  the  underlying  fat  with  the  skin. 

Veins  of  the  Scalp. — In  front  near  the  midUne,  look 
for  and  trace  out  the  Frontal  Vein  {v.  frontalis).  Be 
careful  at  its  lower  part,  not  to  sever  its  communica- 
tion with  the  Ophthalmic  Vein  {v.  ophthalmica  superior) 
at  the  inner  canthus  of  the  eye.  Just  above  this  point, 
look  for  and  trace  out  the  Supra-orbital  Vein  {v.  supra- 


22  DISSECTION  METHODS  AND  GUIDES 

orbitalis)  running  out  horizontally  just  above  the  orbit. 
Just  back  of  the  outer  canthus,  look  for  the  Anterior 
Temporal  Vein  (ramus  anterior  v.  temporalis  swper- 
ficialis).  Trace  it  out,  and  in  its  lower  part  it  will  be 
found  to  join  with  the  Posterior  Temporal  Vein 
(ramus  posterior  v.  temporalis  super jicialis) . 

Clean  the  exposed  upper  portion  of  the  Orbicularis 
Palpebrarum  Muscle  (m.  orbicularis  oculi),  locate  the 
supra-orbital  notch,  a  Uttle  to  the  inner  side  of  the 
middle  of  the  arch  of  the  orbit;  just  above  the  supra- 
orbital notch,  you  will  find  the  Supra-orbital  Artery 
(a.  supraorhitalis)  and  Nerve  (n.  supraorhitalis)  emerg- 
ing from  under  the  upper  edge  of  the  Orbicularis 
Muscle  (m.  orbicularis  oculi).  Trace  both,  and  then 
clean  the  Frontalis  portion  of  the  OccipitofrontaUs 
Muscle  (m.  epicranius).  In  front  of  the  ear,  find  and 
trace  out  the  Auriculotemporal  Nerve.  Pack  tightly 
the  nasopharynx,  mouth,  and  cheeks,  then  sew  the 
lips  together. 

POSTERIOR  TRIANGLE  OF  THE  NECK 

Superficial  Dissection. — Locate  a  point  on  the  lower 
border  of  the  lower  jaw,  halfway  between  angle  and  the 
symphysis.  Make  a  skin  incision  from  this  point  down  to 
the  middle  of  the  clavicle.  This  incision  will  expose  the 
Platysma  Myoides  Muscle  (m.  platysma)  where  it  is  most 
likely  to  be  thick  and  easy  to  recognize.  Do  not  make 
any  knife  incisions  either  along  the  border  of  the  jaw  or 
along  the  clavicle,  but  as  you  dissect  the  skin  up  to  the 
border  of  the  jaw  cut  it  along  the  line  of  the  jaw  with 
a  pair  of  scissors,  and  in  the  same  way  sever  it  as  you 
progress  along  the  line  of  the  clavicle.    Above,  this  will 


POSTERIOR  TRIANGLE  OF  THE  NECK 


23 


Fig.  2. — Scalp,  Face,  and  the  Triangles  of  the  Neck. 
Knife  incisions  are  indicated  by  continuous  red  lines.     Dotted  red  lines  in- 
dicate where  the  skin  should  be  cut  with  scissors. 


i 


24  DISSECTION  METHODS  AND  GUIDES 

obviate  the  danger  of  cutting  the  Platysma  Myoides  {pla- 
tysma)  and  the  Facial  Artery;  and  below,  it  will  avoid 
injury  to  the  Platysma  Myoides  Muscle  (m.  platysma), 
the  Suprasternal  and  the  Supraclavicular  Nerves.  Do 
not  at  this  time  dissect  up  the  skin  in  front  of  the  Stemo- 
mastoid  Muscle  (w.  sternocleidomastoideus) .  Beginning 
in  this  incision,  reflect  the  skin  outwards  and  backwards. 
In  the  lower  part  of  the  incision  reflect  as  much  of  the 
skin  forwards  toward  the  midUne  as  is  necessary  to 
fully  expose  the  Sternomastoid  Muscle  (m.  sternocleido- 
mastoideus) ,  but  do  not  remove  the  skin  from  the  front 
of  the  neck.  Thoroughly  clean  the  exposed  portion 
of  the  Platysma  Myoides  {platysma) ;  then  with  a  pair 
of  scissors  sever  it  about  1  inch  above  the  clavicle; 
reflect  it  forwards  and  upwards.  Clean  the  External 
Jugular  Vein  (v.  jugularis  externa)  as  far  as  the  angle 
of  the  mandible.  Be  careful  not  to  injure  the  Super- 
ficial Cervical  Nerve  (n.  cutaneus  colli).  The  External 
Jugular  Vein  {v.  jugularis  externa)  crosses  this  nerve 
at  right  angles  just  about  the  middle  of  the  Sterno- 
mastoid Muscle  (m.  sternocleidomastoideus).  Tie  the 
External  Jugular  Vein  {v.  jugularis  externa)  below  and 
then  sever  it  above  the  ligature,  and  reflect  it  up- 
wards, but  leave  it  attached  above.  Clean  the  Super- 
ficial Cervical  Nerve  (n.  cutaneus  colli),  working  for- 
wards. Near  its  origin,  at  the  posterior  border  of  the 
Sternomastoid  (sternocleidomastoideus),  you  should  find 
and  trace  out  the  Great  Auricular  Nerve  {n.  auricu- 
laris  magnus),  which  you  will  find  running  upwards 
on  the  surface  of  the  Sternomastoid  {sternocleido- 
mastoideus). At  the  origin  of  the  nerves  just  men- 
tioned,   you   will   find   the    Spinal   Accessory   Nerve 


POSTERIOR  TRIANGLE  OF  THE  NECK  25 

(n.  accessorius) ,  running  downwards  and  backwards; 
clean  this  part  of  it,  then  clean  the  Small  Occipital 
Nerve  (n.  occipitalis  minor),  which  you  will  find  just 
behind  the  Great  Auricular  Nerve  (n.  auricularis 
magnus)  and  running,  parallel  to  it,  close  to  the  poste- 
rior border  of  the  Sternomastoid  Muscle  (m.  sterno- 
cleidomastoideus) .  Clean  the  Sternomastoid  Muscle 
(m.  sternocleidomastoideus) ,  but  do  not  divide  it.  Now, 
if  it  has  not  already  been  done,  find  the  anterior 
border  of  the  Trapezius  Muscle  and  thoroughly  clean 
both  its  superficial  and  deep  surfaces,  taking  care 
not  to  sever  the  Spinal  Accessory  Nerve  {n.  accessorius). 

POSTERIOR  TRIANGLE  OF  THE  NECK 

Deep  Dissection. — Thoroughly  clean  the  Sterno- 
mastoid (sternocleidomastoideus)  for  its  entire  length, 
but  do  not  divide  it.  After  the  thorax  has  been  opened 
it  will  be  possible  to  lift  the  muscle  up,  together  with 
its  sternoclavicular  attachment.  In  order  to  permit 
free  lateral  retraction  it  will  be  necessary  to  divide 
the  Sternomastoid  Branch  of  the  Superior  Thyroid 
Artery  (a.  thyreoidea  superior).  A  little  above  the 
level  of  the  clavicle  you  will  find  running  outwards 
the  Transverse  Cervical  {v.  transversa  colli)  and  Supra- 
scapular (v.  transversa  scapulce)  Branches  of  the  Ex- 
ternal Jugular  Vein  (v.  jugularis  externa).  These  should 
be  traced  out,  then  tied  off,  and  removed.  Now  iden- 
tify the  i^calp^^^^-Anticus  (m.  scalenus  anterior)  and 
the  Scalenus  Medius  (m.  scalenus  medius)  Muscles, 
the  cords  of  the  Cervical  (plexus  cervicalis)  and  Brachial 
(plexus  hrachialis)  Plexuses  emerge  between  them.  On 
the  front  of  the  lower  end  of  the  Scalenus  Anticus,  you 


26  DISSECTION  METHODS  AND  GUIDES 

will  encounter  two  arteries  running  transversely  out- 
wards. The  larger  and  upper  one  is  the  Transverse 
n/  Cervical  Artery,  also  called  the  TransversaUs  (trans- 
versa) Colli;  the  smaller  and  lower  one  is  the  Supra- 
scapular Artery,  which  is  also  called  the  TransversaUs 
Humeri  (a.  transversa  scapulae).  Working  outwards, 
trace  and  clean  both  of  these  arteries.  Running 
downwards  and  inwards,  obliquely  crossing  the  front 
of  the  Scalenus  Anticus  Muscle  (m.  scalenus  anterior), 
you  will  find  the  Phrenic  l^^r^ft  (r).  phrenicus).  Clean 
this  portion  of  it,  working  upwards.  Clean  the  Sub- 
clavian Vein  (v.  subclavia),  beginning  at  the  outer  bor- 
der of  the  first  rib  and  working  outwards.  In  the  same 
way  clean  the  corresponding  portion  of  the  Subclavian 
Artery  (a.  subclavia).  Do  not  at  this  time  interfere 
in  any  way  with  the  inner  portions  of  these  two  vessels. 
Now  clean  the  primary  cords  of  the  Brachial  Plexus 
(plexus  brachialis). 

ANTERIOR   TRIANGLE   OF   THE   NECK,   LOWER  PART 

Finish  the  removal  of  the  skin  on  the  front  of  the 
neck  by  dissecting  it  upwards  to  the  border  of  the  jaw. 
In  the  same  way  reflect  upwards  the  Platysma  Myoides. 
The  Sternomastoid  should  already  have  been  thor- 
oughly cleaned  to  allow  of  its  being  freely  retracted 
outwards,  in  order  to  expose  the  Descendens  Hypo- 
glossi  Nerve  (ramus  descendens  n.  hypoglossi)  lying  on 
the  front  of  the  sheath  of  the  great  vessels.  It  will  be 
found  emerging  from  behind  the  Internal  Jugular 
Vein  (v.  jugularis  interna)  or  from  behind  the  Superior 
Thyroid  Vein  (v.  thyreoidea  superioris),  usually,  in 
either  case,  just  on  a  level  with  the  Cricothyroid  Mem- 


ANTERIOR  TRIANGLE  OF  THE  NECK,  LOWER  PART      27 

brane  {memhrana  cricothyreoidea  vel  conus  elasticus). 
Clean  it  and  the  Ansa  Hypoglossi,  which  is  formed  by 
the  continuity  or  union  of  the  Descehdens  Hypoglossi 
(n.  descendens  cervicis)  with  the  Communicantes  Hy- 
poglossi. Occasionally  the  Descendens  Hypoglossi, 
instead  of  running  down  on  the  front  of  the  sheath  of 
the  great  vessels,  is  found  within  the  sheath.  The  Loop 
of  the  Ansa  may  be  at  any  level  between  the  lower 
border  of  the  Occipital  Artery  and  the  posterior  belly 
of  the  Omohyoid  Muscle  (m.  omohyoideus) .  Should 
you  have  any  trouble  in  locating  these  nerves,  just 
remember  that  the  anterior  belly  of  the  Omohyoid 
(m.  omohyoideus)  is  supplied  by  the  Descendens 
Hypoglossi,  and  that  the  posterior  belly  of  the  Omo- 
hyoid (m.  omohyoideus)  is  supplied  by  the  Ansa.  So, 
by  carefully  cleaning  this  muscle,  it  is  easy  to  find  the 
nerves  supplying  it  and  to  trace  them  to  their  origin. 
Again,  it  should  be  remembered  that  the  Ansa  is 
derived  by  two  roots,  one  from  the  Second  and  one 
from  the  Third  Cervical  Nerves,  in  front  of,  but  in 
exactly  the  same  way  as  are  both  the  Great  Auricular 
(n.  auricularis  magnus)  and  the  Superficial  Cervical 
(n.  cutaneus  colli)  Nerves.  Therefore,  it  should  prove 
an  easy  matter  to  trace  the  Ansa  down  from  its  origin. 
Now,  begin  in  the  midline  and  clean,  in  the  follow- 
ing order,  first,  the  Sternohyoid  (w.  sternohyoideus) ; 
second,  the  Omohyoid  (m.  omohyoideus);  third,  the 
Thyrohyoid  (m.  thyreohyoideus)  Muscles.  Then  re- 
move all  of  the  loose  areolar  fat  lying  beneath  these 
muscles.  Clean  the  Thyroid  Gland  {glandula  thyreoi- 
dea),  and  clear  away  all  the  loose  fatty  tissue  lying 
below  it  and  on  the  front  of  the  trachea,  and  in  doing 


28  DISSECTION  METHODS  AND  GUIDES 

SO  be  careful  not  to  injure  the  thyroid  vessels,  espe- 
cially the  Inferior  Thyroid  Veins  (vv.  thyreoidece  in- 
feriores).  Clean  the  Stylohyoid  Muscle  (m.  stylo- 
hyoideus),  then  the  posterior  belly  of  the  Digastric 
(m.  digastricus),  but  do  not  disturb  anything  in  the 
digastric  triangle.  Locate  the  External  Laryngeal 
Nerve  (ramus  externus  n.  laryngeus  superior))  you  will 
find  it  behind  the  upper  part  of  the  Sternothyroid 
Muscle  (m.  sternothyreoideus)  just  behind  the  oblique 
ridge  on  the  wing  of  the  thyroid  cartilage.  By  tracing 
this  nerve  backwards  you  will  encounter  the  Superior 
Laryngeal  Nerve  {n.  laryngeus  superior),  which  should 
now  be  cleaned. 

Clean  the  Internal  Jugular  Vein  {v.  jugularis  interna), 
ligate  and  cut  away  any  small  veins  which  interfere. 
Clean  the  Common  Carotid  Artery  (a.  carotis  com- 
munis). Look  in  the  thorax  for  the  Phrenic  Nerve 
(n.  phrenicus)  and  follow  it  up  into  the  neck.  In  the 
same  way  follow  up  and  clean  the  Pneumogastric 
Nerve  (n.  vagus).  Follow  up  the  Thoracic  Duct 
{ductus  thoracicus)  from  within  the  chest  and  clean 
the  Left  Subclavian  Vein  {v.  subclavia). 

SUBCLAVIAN  TRIANGLE 

Clean  the  right  Subclavian  Vein  (v.  subclavia),  and 
in  doing  so  be  careful  not  to  injure  the  Right  Lymph- 
atic Duct  {ductus  lymphaticus  dexter),  which  you  will 
find  entering  the  Subclavian  Vein  {v.  subclavia)  from 
above,  just  external  to  the  union  with  the  Internal 
Jugular  Vein  {v.  jugularis  interna).  From  within  the 
chest,  trace  upwards  the  Recurrent  Laryngeal  Nerves 
{nn.  laryngei  inferiores).    Clean  the  Subclavian  Artery 


ANTERIOR  TRIANGLE  OF  THE  NECK,  UPPER  PART       29 

{a.  suhclavia),  the  Thyroid  Axis  (truncus  thyreocervi- 
calis),  and  its  branches. 

In  cleaning  the  Inferior  Thyroid  Artery  (a.  thyreoidea 
inferior),  be  on  the  lookout  for  the  Gangliated  Cord 
(truncus  sympatheticus)  of  the  Sympathetic,  which  you 
will  often  find  crossing  it  in  front.  Clean  the  Gan- 
gliated Cord  (truncus  sympatheticus)  and  its  Middle 
Cervical  Ganglion  (ganglion  cervicale  medium) ;  trace  it 
upwards  first,  then  follow  it  downwards  into  the  chest. 

ANTERIOR  TRIANGLE  OF  THE  NECK,  UPPER  PART 

Before  working  out  this  region,  it  will  be  necessary 
to  find  the  Facial  Nerve  (n.  facialis)  and  free  it,  so 
that  it  can  be  freely  lifted  up  or  retracted;  otherwise  it 
is  almost  sure  to  be  destroyed.  To  find  the  main 
trunk  of  the  Facial  Nerve  (n.  facialis),  first  locate  the 
transverse  process  of  the  Atlas,  then  in  front  of  this 
feel  for  the  styloid  process.  You  should  find  the 
Facial  Nerve  (n.  facialis)  crossing  the  base  of  the 
styloid  process  on  its  outer  side.  This  nerve  stands 
out  far  more  than  it  is  shown  to  do  in  most  plates. 
If  the  subject  happens  to  be  very  fat,  or  to  have  a 
thick,  short  neck,  it  may  prove  easier  to  find  the 
Facial  Nerve  (n.  facialis)  in  another  way.  This  second 
manner  of  finding  the  Facial  Nerve  (n.  facialis)  will  be 
more  intelligible  if  you  understand  the  following 
points:  At  just  about  the  level  of  the  angle  of  the 
mandible  the  External  Jugular  Vein  (v.  jugularis  ex- 
terna) is  formed  by  the  confluence  of  two  veins.  The 
anterior  one  of  these  is  the  Temporomaxillary  Vein 
(v.  facialis  posterior),  the  posterior  one  is  the  Posterior 
Auricular    (v.   auricularis    posterior).     The    Temporo- 


30  DISSECTION  METHODS  AND  GUIDES 

maxillary  Vein  {v.  facialis  posterior)  originates  in  the 
substance  of  the  Parotid  Gland  {glandulce  parotis) 
by  the  confluence  of  two  veins.  The  anterior  one  of 
these  is  the  Internal  Maxillary  Vein  (v.  maxillaris 
interna),  the  posterior  is  the  Common  Temporal  Vein 
(v.  temporalis  communis).  The  Internal  Maxillary 
Vein  (v.  maxillaris  interna)  is  much  the  larger  and  is  the 
most  important  one  in  this  dissection.  Note  that  it  is 
always  the  anterior  branch  of  any  two  of  the  afore- 
mentioned veins  which  is  important  to  us  at  this  time. 
In  the  substance  of  the  Parotid  Gland  {glandulce 
parotis),  the  Facial  Nerve  (n.  facialis),  by  dividing  up, 
forms  what  is  called  the  Pes  Anserinus.  Of  these  divi- 
sions the  largest  two  are:  First,  the  Temporofacial, 
which  runs  upwards  and  forwards;  second,  the  Cervico- 
facial, which  runs  forwards  and  downwards.  For  this 
dissection  it  is  important  to  note  two  things:  First, 
that  the  Internal  Maxillary  Vein  {v.  maxillaris  in- 
terna) is  superficial  to  and  crosses  the  Cervicofacial 
Division;  second,  that  the  Cervicofacial  is  superficial 
to  and  crosses  the  Common  Temporal  Vein  (v.  tempo- 
ralis communis).  You  have  only  to  find  the  Internal 
Maxillary  Vein  {v.  maxillaris  interna)  in  order  to  find  the 
Cervicofacial  Division  of  the  Facial  Nerve.  Therefore, 
carefully  follow  up  the  External  Jugular  Vein  (v. 
jugularis  externa) ,  clearing  it  anteriorly  without  molest-^ 
ing  its  posterior  branches.  In  the  same  way  follow  up 
the  Temporomaxillary  {v.  facialis  posterior),  and  then 
the  Internal  Maxillary  {v.  maxillaris  interna),  under 
which  you  will  find  the  Cervicofacial  Nerve,  which  you 
should  then  trace  backwards  to  the  main  trunk  of  the 
Facial   (n.  facialis).     Clean  the  main   trunk   of  the 


ANTERIOR  TRIANGLE  OF  THE  NECK,  UPPER  PART       31 

Facial  Nerve  (n.  facialis)  and  follow  out  its  branches 
through  the  Parotid  Gland  (glandulw  parotis)  until 
they  emerge  from  the  gland.  Make  sure  that  you 
have  this  nerve  quite  free,  so  that  it  can  be  readily 
retracted.  Do  not  remove  any  more  of  the  skin  from 
the  face  than  is  absolutely  necessary  to  the  full  ex- 
posure of  the  Parotid  Gland.  Clean  the  External 
Carotid  Artery  (a.  carotis  externa)  and  follow  out  first 
the  Postauricular  Artery  (a.  auricularis  posterior),  and 
then  the  Temporal  Artery  (a.  temporalis  superficialis) . 
Now  clean  as  much  as  is  easily  accessible  of  the  In- 
ternal Maxillary  Artery  (a.  maxillaris  interna).  Just 
behind  the  neck  of  the  mandible,  or  lying  on  the  cap- 
sular hgament,  look  for  the  Auriculotemporal  (n. 
auriculotemporalis)  Branch  of  the  Mandibular  Nerve 
(n.  mandibularis)  and  trace  it  upwards.  After  all  of 
the  afore-mentioned  structures  have  been  fully  worked 
out,  get  rid  of  all  fat  and  entirely  remove  the  Parotid 
Gland.  Sever  the  Stylomandibular  Ligament  {I.  stylo- 
mandihulare)  and  then  clean  the  Styloglossus  and 
Stylopharyngeus  Muscles  and  the  Glossopharyngeal 
Nerve  {n.  glossopharyngeus) .  The  Stylopharyngeus 
Muscle  is  supplied  by  the  Glossopharyngeal  Nerve 
(n.  glossopharyngeus). 

Clean  the  Internal  Jugular  Vein  (v.  jugularis  in- 
terna) and  the  Internal  Carotid  Artery  (a.  carotis 
interna).  Trace  upwards  the  Superior  Laryngeal  Nerve 
{n.  laryngeus  superior)  and  then  clean  the  Pneumo- 
gastric  Nerve  {n.  vagus). 

Now  remove  the  sheaths  of  the  foregoing  structures, 
then  clean,  in  the  following  order:  First,  the  Superior 
Thyroid  Artery  (a.  thyreoidea  superior);  second,  the 


32  DISSECTION  METHODS  AND  GUIDES 

exposed  portion  of  the  Lingual  Artery  (a.  lingualis); 
third,  the  Ascending  Pharyngeal  Artery  (a.  pharyngea 
ascendens) ;  fourth,  the  Facial  Artery  (a.  maxillaris 
externa)  as  far  only  as  the  border  of  the  mandible. 
Clean  the  anterior  belly  of  the  Digastric  Muscle  (m. 
digastricus)  and  free  the  Submandibular  Gland  {glan- 
dula  submaxillaris) ,  so  that  it  can  be  reflected  upwards 
and  forwards.  Clean  the  Mylohyoid  Muscle  (w.  mylo- 
hyoideus),  and  in  doing  so  be  careful  not  to  injure  the 
Hypoglossal  Nerve  (n.  hypoglossus) . 

THE  REGION  OF  THE  FACE 

Remove  all  of  the  skin  from  the  entire  face,  but  in 
doing  so  do  not  attempt  to  remove  any  of  the  under- 
lying fat.  It  is  good  practice  not  to  make  any  pre- 
liminary knife  incisions  anywhere  on  the  face  itself, 
but  when  the  skin  has  been  dissected  up  close  to  any 
natural  opening,  such  as  the  mouth,  nose,  and  eye, 
to  then  trim  it  around  the  opening  with  a  pair  of  scissors. 
The  skin  having  been  removed,  but  the  superficial  fat 
left  undisturbed,  you  should  complete  the  dissection  of 
the  Facial  Nerve.  Then  work  out  the  Superficial 
Temporal  Artery  (a.  temporalis  superficialis)  and  care- 
fully follow  out  its  Transverse  Facial  (a.  transversa 
faciei)  Branch,  which  will  be  found  about  a  finger's 
breadth  below  and  parallel  to  the  Zygoma.  Just 
below  this  artery  you  should  find  and  clean  the  Parotid 
(Stenson's)  Duct  {ductus  parotideus). 

Working  from  below  upwards,  clean  the  facial  por- 
tion of  the  Platysma,  following  its  converging  fibers  to 
the  corner  of  the  mouth.  It  may  be  that  in  this  situa- 
tion the  Platysma  is  far  too  attenuated  and  thin  to 


THE  REGION  OF  THE  FACE  33 

allow  of  its  being  followed  to  the  corner  of  the  mouth, 
but  even  then,  a  fairly  well-defined  bundle  of  its  upper- 
most muscular  fibers  will  be  found  running  horizontally 
outwards  and  backwards  from  the  corner  of  the  mouth. 
This  bundle  of  the  Platysma  constitutes  what  is  usually 
called  the  Risorius  Muscle. 

Begin  at  the  border  of  the  mandible  and  follow  up 
the  Facial  Artery  (a,  maxillaris  externa);  be  careful 
not  to  cut  its  Submental  (a.  submentalis)  Branch, 
which  is  usually  given  off  at  the  border  of  the  jaw. 
If  you  do  sever  it,  tie  it  on  again  with  a  piece  of  thread. 

Clean  the  Facial  Artery  until  you  reach  the  point 
where  it  dips  under  the  Risorius.  On  the  side  of  the 
nose,  close  to  the  inner  canthus  of  the  eye,  find  and  clean 
the  Angular  Artery  (a.  angularis) ,  working  down  as  far 
as  the  edge  of  the  Zygomaticus  Minor  Muscle.  Now 
finish  cleaning  the  Orbicularis  Palpebrarum  (w.  orbicu- 
laris oculi),  and  then  clean,  in  exactly  the  following 
order :  First,  the  Pyramidalis  Nasi  (m.  procerus) ;  second, 
the  Levator  Labii  Superioris  Alseque  Nasi;  third,  the 
Levator  Labii  Superioris  (proprius).  Next  clean  the 
Zygomaticus  Minor,  the  Zygomaticus  Major,  and  the 
Risorius;  after  which  clean  that  portion  of  the  Facial 
Artery  (a.  maxillaris  externa)  underlying  them.  Clean 
the  Orbicularis  Oris,  then  retract  the  Risorius  down- 
wards and  follow  out  the  Superior  Coronary  Artery 
(a.  labialis  superior).  Retract  the  Risorius  upwards 
and  trace  out  the  Inferior  Coronary  Artery  (a.  labialis 
inferior).  Both  of  these  arteries  are  given  off  by  the 
Facial  under  cover  of  the  Risorius. 

Trace  out  the  Inferior  Labial  Artery,  and  then  clean 
the  Depressor  Anguli  Oris  (m.  triangularis  oris)  and 


34  DISSECTION  METHODS  AND  GUIDES 

the  Depressor  Labii  Inferioris  (m.  quadratus  labii 
inferioris).  Clean  the  Masseter  Muscle,  after  which 
clean  the  Buccinator  Muscle,  but  be  careful  not  to 
sever  the  Parotid  Duct,  the  outer  end  of  which  should 
be  secured  by  a  stitch  to  the  fascia  of  the  Masseter 
Muscle. 

Clean  the  Temporal  Muscle  (m.  temporalis)  and 
remove  all  the  fat  from  behind  the  arch  of  the  Zygoma, 
especially  in  the  front  part  of  the  arch.  Thoroughly 
clear  away  and  remove  all  the  fat  from  the  entire 
region  of  the  face.  In  doing  so,  use  a  pair  of  scissors 
which  are  ''curved  on  the  flat." 

REMOVAL  OF  THE  BRAIN 

From  the  middle  of  the  forehead,  make  a  longitudinal 
incision  in  the  midhne,  as  far  back  as  the  Inion  {pro- 
tuherantia  occipitalis  externa).  At  right  angles  to  this 
cut,  make  a  transverse  one,  running  from  one  ear  to  the 
other.  Both  of  these  cuts  should  go  through  the  peri- 
osteum. Turn  down  the  four  flaps  thus  formed  and 
fully  expose  the  skull.  Saw  off  the  Calva  at  a  level 
which,  in  front,  should  be  a  finger's  breadth  above  the 
eye-socket,  and  behind  it  should  be  about  the  same 
distance  above  the  Inion  {protuberantia  occipitalis  ex- 
terna). You  will  find  it  easier  to  do  this  neatly  if  you 
first  encircle  the  skull,  at  the  right  level,  with  a  piece 
of  string,  and  then  saw  a  slight  groove  all  the  way 
around  before  sawing  all  the  way  through  the  bone. 
When  it  is  imperative  that  the  brain  be  absolutely 
uninjured,  then  it  is  necessary  to  avoid  sawing  all  the 
way  through  the  bone  at  any  point,  but  to  saw  as 
nearly  through  the  bone  as  can  safely  be  done,  and 


REMOVAL  OF  THE  BRAIN  35 

then  to  cut  or  break  through  the  inner  table  of  the 
skull  with  an  osteotome  or  sharp  flat  chisel. 

After  the  Calva  has  been  separated  from  the  skull, 
Hft  it  up  slightly  in  front,  and  separate,  in  its  longi- 
tudinal midline,  the  attachment  of  the  Dura  Mater. 
Study  the  disposition  of  the  Meningeal  Arteries  and 
the  Pacchionian  Bodies  (granulationes  arachnoideales) . 
Slit  open  the  Superior  Longitudinal  Sinus  (sinus  sagit- 
talis  superior)  and  note  the  cords  of  WilUs,  the  Pacchi- 
onian Bodies  {granulationes  arachnoideales),  and  com- 
munications with  Parasinoidal  Spaces.  Using  a  pair 
of  blunt-pointed  scissors,  cut  the  dura  away  from 
the  Superior  Longitudinal  Sinus  (sinus  sagittalis  supe- 
rior) on  both  sides;  then  cut  the  Dura  Ma+er  (en- 
cephali)  transversely  downwards  on  each  side,  in  the 
same  way  that  the  scalp  was  cut.  Remove  any  sharp 
points  or  sphnters  of  bone  from  the  sawn  edge  of  the 
skull.  Turn  the  triangular  flaps  of  Dura  Mater  over 
the  margin  of  the  skull  to  protect  your  hands  from 
its  sharp  edges.  Gently  lift  up  the  frontal  lobes  and 
snip  off  the  Falx  Cerebri  as  closely  as  you  can  to  the 
Crista  Galli.  Then  divide  the  filaments  of  the  Olfac- 
tory Nerves  (nn.  olfactorii)  and,  following  back,  cUp 
the  Optic  (n.  opticus),  Third  (n.  oculomotorius) ,  and 
Fourth  (n.  trochlearis)  Nerves,  the  Infundibulum,  and 
the  Internal  Carotid  Arteries  (aa.  carotides  internee). 
On  both  sides  divide  the  Tentorium  CerebelU  as  closely 
as  is  possible  to  the  bone.  Then  divide  the  Fifth 
(n.  trigeminus).  Sixth  (n.  ahducens),  Seventh  (n. 
facialis),  and  Eighth  (n.  acusticus)  Nerves.  Tilt  the 
head  to  the  opposite  side  while  doing  so.  After  the 
Tentorium  has  been  divided  on  both  sides,  tilt  the 


36  DISSECTION  METHODS  AND  GUIDES 

head  well  back,  support  the  brain  with  your  hand,  and 
allow  it  to  turn  out  backwards  far  enough  to  permit 
of  your  dividing  the  remaining  cranial  nerves  and  the 
vertebral  arteries;  draw  slightly  on  the  spinal  cord, 
and  (now  for  the  first  time  using  a  knife)  cut  the  cord 
at  as  low  a  point  as  can  conveniently  be  reached. 
If,  after  opening  the  dura,  you  find  that  the  brain  is 
too  soft  to  permit  of  its  removal,  no  attempt  should 
be  made  to  remove  it  intact.  Instead,  empty  out  as 
much  of  it  as  will  come  away  by  gentle  shaking,  then 
thoroughly  wash  out  the  rest  of  it  with  hot  water.  This 
will  afford  an  excellent  opportunity  to  study  the 
cerebral  vessels,  the  Falx,  Tentorium,  and  some  of  the 
cranial  nerves.  The  Tentorium  should  then  be 
trimmed  away  close  to  its  attachments  and  the  cere- 
bellum washed  out,  thereby  exposing  the  arteries  of 
the  base  of  the  brain  and  the  rest  of  the  cranial  nerves. 
Identify  each  of  the^  cranial  nerves  as  it  pierces  the 
dura,  and  identify  the  arteries.  Slit  open  and  follow 
out  the  Lateral  Sinus  {sinus  transversus) ,  the  Superior 
(s.  petrosus  superior)  and  Inferior  (s.  petrosus  inferior) 
Petrosal  Sinuses,  but  do  not  disturb  the  Cavernous 
Sinus  (s.  cavernosus).  Note  the  frontal  air-sinuses  and 
find  out  if  they  communicate  with  each  other;  as  a 
rule  they  do  not. 

ORBIT  AND  EYE 

Saw  off  the  vertical  portion  of  the  frontal  bone  on  a 
level  with  the  cerebral  surface  of  the  orbital  plates. 
This  saw-cut  should  extend  all  the  way  back  to  the 
parietal,  in  order  that  the  entire  frontal  portion  may 
be  removed.  Lift  up  and  remove  the  dura  from  both 
orbital  plates  as  far  back  as  the  sphenoidal  fissure. 


ORBIT  AND  EYE  37 

Free  the  periosteum  and  the  overlying  soft  parts  from 
the  upper  and  outer  margin  of  the  arch  of  the  orbit. 
Saw  through  the  arch  of  the  orbit  in  two  places,  one 
being  just  over  the  inner  can  thus,  and  the  other  over 
the  outer  canthus,  of  the  eye.  A  smart  blow  with  a 
mallet  should  readily  break  away  the  intervening  bone 
and  fracture  the  orbital  plate.  The  blow  should  be 
directed  upwards.  Carefully  separate  the  soft  parts 
from  the  roof  of  the  orbit,  and  with  bone-forceps 
trim  away  all  of  the  roof  as  far  back  as  the  Lesser 
Wing  (ala  parva)  of  the  Sphenoid.  Saw  through  the 
base  of  the  Lesser  Wing  (ala  parva)  of  the  Sphenoid, 
cutting  almost  into  the  Optic  Foramen.  Be  careful 
not  to  cut  the  optic  nerve,  and  try  to  retain  the  ante- 
rior clinoid  process  intact.  Break  away  the  Lesser 
Wing  of  the  Sphenoid  and  lay  widely  open  both  the 
Optic  Foramen  and  the  Sphenoidal  Fissure  {fissura 
orhitalis  superior) . 

Carefully  clear  away  all  fat  from  the  inner  half  of 
exposed  portion  of  the  eye.  '  Locate  the  Superior 
Oblique  Muscle  {ohliquus  oculi  superior),  and  on  the 
back  part  of  its  upper  surface,  look  for  the  Fourth 
Nerve  (n.  trochlearis) .  Trace  this  nerve  backwards 
as  far  as  the  Tentorium  CerebelU.  Do  not  attempt  to 
seize  it  with  your  forceps,  for  it  is  soft  and  easily 
torn.  Instead,  you  should  cut  the  fascia  along  each 
side  of  it,  close  to  it.  Then  you  can  lift  it  out  of  its 
bed  with  your  knife  handle.  Now  go  to  the  outer 
half  of  the  exposed  upper  surface  of  the  eye  and  care- 
fully isolate  the  Lacrimal  Gland  (glandula  lacrimalis) . 
In  doing  so  be  careful  not  to  injure  the  Lacrimal 
(n.  lacrimalis)  Branch  of  the  Ophthalmic  Nerve.     Iso- 


38  DISSECTION  METHODS  AND  GUIDES 

late  this  nerve  from  the  loose  cellular  fat  in  which 
it  is  lying,  but  do  not  attempt  to  trace  it  backwards. 
Clear  away  all  of  the  remaining  fat  from  the  upper 
surface  of  the  eye.  On  the  front  of  the  apex  of  the 
petrous  bone,  expose  the  Gasserian  or  Trigeminal 
Ganglion  {g.  semilunar e)  by  removing  the  layer  of 
dura  which  covers  it.  Trace  the  Ophthalmic  Nerve 
forwards  through  the  outer  wall  of  the  Cavernous  Sinus; 
then  follow  the  Lacrimal  Nerve  forwards  until  you 
reach  the  part  you  have  already  cleaned.  Halfway 
between  the  anterior  and  posterior  clinoid  processes, 
in  a  little  triangle  formed  by  the  attachments  of  the 
dura,  look  for  the  Third  or  Oculomotor  Nerve  (n. 
oculomotorius) ,  and  trace  it  forwards  until  it  divides 
into  its  upper  and  lower  divisions.  Passing  between 
these  divisions  you  will  see  the  Nasal  (n.  nasociliaris) 
Branch  of  the  Ophthalmic  Nerve.  Look  for  the 
Sixth  or  Abducent  Nerve  {n.  abducens).  You  will  find 
it  in  the  floor  of  the  Cavernous  Sinus  or  in  the  notch  on 
the  side  of  the  Dorsum  Sellse;  trace  it  forwards  to  the 
interval  between  the  two  heads  of  the  External  Rectus 
Muscle.  Clean  the  Levator  Palpebrae  Superioris 
Muscle  and  the  Superior  Rectus  Muscle  (m.  rectus 
oculi  superior).  Clean  the  upper  division  of  the  Third 
Nerve  {n.  oculomotorius),  following  it  out  to  its  termi- 
nations in  the  two  muscles  just  mentioned.  Do  not 
molest  the  lower  division  of  the  Third  Nerve  at  this 
time.  Clean  the  Superior  Ophthalmic  Vein,  the 
Ophthalmic  Artery,  and  its  Supra-orbital  Branch. 
Clean  away  every  remaining  atom  of  fat  from  this 
region  of  the  eye.  Both  eyes  should  be  dissected,  up 
to  this  point.    Keep  the  left  eye  in  its  present  state  for 


SPHENOPALATINE  FOSSA,  INTERNAL  MAXILLARY  ARTERY  39 

later  comparisons,  and  proceed  on  the  right  side  to  do 
the  deep  lateral  dissection.  Using  the  handle  of  your 
knife,  carefully  separate  the  soft  parts  from  the  outer 
margin  and  outer  wall  of  the  orbit;  then  cut  through 
the  malar  bone  into  the  Sphenomaxillary  Fissure 
(fissura  orhitalis  inferior).  Remove  the  outer  wall  of 
the  orbit,  especially  its  back  part.  Bone-forceps  will 
serve  you  best  for  this  purpose.  Clean  away  all  the  fat 
and  then  divide  the  External  Rectus  (m.  rectus  oculi 
externus)  close  to  the  eyeball,  and  reflect  it  backwards. 
Now  clean  the  lower  division  of  the  Third  Nerve  in. 
oculomotorius)  at  its  back  part;  look  for  a  short, 
thick  branch  running  upwards;  this  goes  to  the  CiHary 
Ganglion  (g.  ciliare)  and  will  serve  as  a  guide  to  it. 
Clean  the  Optic  Nerve  and  finish  cleaning  the  Oph- 
thalmic Artery  and  the  Ophthalmic  Vein. 

SPHENOPALATINE  FOSSA  (J.  pterygopalatina)  AND  INTERNAL  MAX- 
ILLARY ARTERY   (a.  maxillaris  interna) 

After  having  completed  the  deep  lateral  dissection 
of  the  right  orbit,  proceed,  on  the  same  side,  to  detach 
the  soft  parts  from  the  facial  surface  of  the  malar  bone 
and  the  zygomatic  arch.  Saw  through  the  Zygomatic 
Process  immediately  in  front  of  the  temporomandibu- 
lar articulation. 

Saw  the  malar  away  from  the  maxilla  in  such  a  way 
that  the  Maxillary  Antrum  (sinus  maxillaris)  will  be 
opened.  It  is  not  necessary  to  saw  entirely  through, 
as  it  is  more  convenient  to  pry  or  wrench  the  malar 
loose  after  sawing  far  enough,  so  that  it  is  mostly  held 
in  place  by  the  orbital  plate  of  the  maxilla.  The 
malar    and    zygomatic    arch    having   been    removed, 


40  DISSECTION  METHODS  AND  GUIDES 

remove  the  fat  and  clean  the  Temporal  Muscle,  then 
saw  off  the  coronoid  process  and  reflect  the  Temporal 
Muscle  upwards,  fastening  it  up  out  of  your  way  by  a 
stitch.  Open  the  temporomandibular  joint,  and  with 
a  pair  of  blunt-pointed  scissors  trim  away  all  of  the 
outer  part  of  the  capsule  in  order  to  show  the  two 
joint  cavities,  the  interarticular  fibrocartilage,  and  the 
attachment  to  that  cartilage  of  the  upper  head  of  the 
External  Pterygoid  Muscle.  Saw  the  ramus  of  the 
jaw  horizontally  about  one-third  of  the  distance  down 
from  the  condyle  to  the  angle.  It  is  better  not  to  saw 
entirely  through  the  ramus,  but  to  complete  the  saw- 
cut  by  fracturing  the  bone.  You  must  keep  well 
above  the  middle  of  the  ramus  to  avoid  injuring  the 
Inferior  Dental  Nerve.  Sever  the  insertion  of  the 
External  Pterygoid  in  front  of  the  neck,  then  detach 
the  capsule,  disarticulate,  and  remove  the  bone. 
Using  a  pair  of  blunt-pointed  scissors,  remove  all  of 
the  capsule  and  the  interarticular  cartilage.  Be 
careful  in  doing  so,  not  to  injure  the  mandibular  divi- 
sion of  the  Fifth  Nerve  or  the  Chorda  Tympani  Nerve, 
which  are  close  behind  and  internal  to  the  capsule. 
It  often  happens  that  the  Internal  Maxillary  Artery 
lies  under  cover  of  the  External  Pterygoid  Muscle, 
in  which  case  that  muscle  should  be  shredded  away 
piecemeal  and  entirely  removed,  and  with  it  all  fat. 
If  the  artery  is  superficial  to  the  lower  head  of  the 
External  Pterygoid,  then  clean  the  artery  before 
removing  the  muscle.  The  artery  must  be  cleaned 
and  the  muscle  must  be  removed;  the  order  in  which 
you  do  so  must  depend  upon  their  disposition.  Remove 
all  of  the  outer  wall  of  the  Maxillary  Antrum  (sinus 


PHARYNX  41 

maxillaris) ,  then  as  much  of  the  roof  as  is  external  to  the 
infra-orbital  canal.  Break  up  and  remove  all  of  the 
posterior  wall.  The  Sphenopalatine  Fossa  (/.  ptery- 
gopalatina)  is  now  widely  open,  so  that  everything 
in  this  region  is  easily  accessible.  Using  two  pairs  of 
dissecting  forceps,  clear  away  all  fat.  Finish  cleaning 
the  internal  maxillary  artery  and  isolate  its  branches. 
Isolate  the  Sphenopalatine  (Meckel's)  Ganglion,  Max- 
illary (n.  maxillaris)  Division  of  the  Fifth  (n.  trigeminus) , 
and  the  Infra-orbital  Nerves.  Now  clean  the  Man- 
dibular Division  of  the  Fifth  (n.  trigeminus) ,  internal  to 
it  as  it  emerges  from  the  foramen  ovale;  find  the  Otic 
Ganglion.  Clean  the  Lingual  Nerve  and  the  Chorda 
Tyjnpani.     Clean  the  Sphenomandibular  Ligament. 

PHARYNX 

Clean  the  left  Buccinator  Muscle.  Remove  the 
zygomatic  arch  and  with  it  the  Masseter  and  both 
Zygomatic  Muscles.  Saw  vertically  through  the 
mandible  just  back  of  the  attachment  of  the  Buc- 
cinator Muscle,  then  saw  off  the  coronoid  process. 
Disarticulate  and  remove  the  ramus  of  the  mandible. 
Entirely  remove  both  the  External  and  the  Internal 
Pterygoid  Muscles.  In  removing  the  latter  be  care- 
ful not  to  destroy  the  Tensor  Palati  (m.  tensor  veli 
palatini).  Remove  the  Sternomastoid  Muscle  (m. 
sternocleidomastoideus) ,  sever  the  posterior  belly  of  tlie 
Digastric  Muscle  close  to  its  osseous  attachment,  and 
reflect  it  downwards  and  forwards.  Clean  the  Stylo- 
pharyngeus  and  Styloglossus  Muscles,  then  clean  the 
Tensor  Palati  (w.  tensor  veli  palatini)  as  far  as  the 
hamular  process.     Clean  the  Inferior  Constrictor,  then 


42  DISSECTION  METHODS  AND  GUIDES 

the  Middle  Constrictor.  Finish  cleaning  the  Buccina- 
tor, carefully  working  out  its  junction  with  the  Superior 
Constrictor  (m.  constrictor  pharyngis  superior),  which 
forms  the  Pterygomandibular  Ligament.  Clean  the 
Superior  Constrictor  and  free  its  upper  border  from  the 
Pharyngeal  Aponeurosis  which  there  forms  the  Sinus 
of  Morgagni.  In  dping  so  be  careful  not  to  cut  the 
Levator  Palati  (m.  levator  veil  palatini).  Sever  both 
Styloid  Processes  and  reflect  them  forwards,  along 
with  the  muscles  attached  to  them.  Thrust  your 
fingers  into  the  interval  between  the  esophagus  and 
the  Left  Longus  Colli  Muscle.  Tear  through  the 
loose  areolar  tissue  and  enlarge  the  space  until  you 
are  able  to  thrust  your  hand  through  to  thje  other 
side.  Keep  enlarging  this  space  upwards,  separating 
the  pharynx  from  the  vertebrae  and  prevertebral 
muscles  until  you  reach  the  basilar  process.  Detach 
the  common  central  tendon  of  the  pharyngeal  constric- 
tors from  the  Pharyngeal  Spine  {tuherculum  pharyn- 
geum).  With  your  hand  retract  forwards  all  of  the 
soft  parts,  insert  a  saw  and  cut  transversely  upwards 
through  the  base  of  the  skull.  This  saw-cut  should 
be  immediately  anterior  to  the  attachment,  on  each 
side,  of  the  Rectus  Capitis  Anticus  Major  (w.  longus 
capitis)  to  the  basilar  process.  All  the  soft  parts 
anterior  to  these  muscles  should  be  retracted  well 
forwards  and  be  protected  from  the  saw.  For  this 
latter  purpose  it  is  convenient  to  use  as  a  retractor 
a  strip  of  cloth  or  a  piece  of  bandage.  In  order  the 
sooner  to  abandon  the  spinal  column  to  those  who  may 
be  working  out  the  spinal  cord,  it  is  now  a  convenient 
time  to  work  out  the  prevertebral  region.     So  cut  off 


SOFT  PALATE  43 

the  esophagus  and  trachea  just  above  the  level  of  the 
bifurcation  of  the  latter,  and  lay  aside  the  larynx, 
nasopharynx,  etc.,  to  be  finished  later. 

PREVERTEBRAL  REGION 

Remove  the  prevertebral  fascia,  and,  on  both  sides, 
clean  in  the  following  order:  First,  the  Rectus  Capitis 
Anticus  Major  (m.  longus  capitis);  second,  the  lower 
half  of  the  Longus  Colli;  third,  the  Scalenus  Anticus 
(m.  scalenus  anterior).  On  one  side  remove  the  Rectus 
Capitis  Major  (m.  longus  capitis)  and  Anterior  Scalene 
(m.  scalenus  anterior).  Clean  the  Cervical  Nerves  and 
as  much  as  is  easily  accessible  of  the  Vertebral  Artery 
(a.  vertebralis) .  Clean:  First,  the  Scalenus  Medius; 
second,  the  upper  half  of  the  Longus  Colli;  third,  the 
Rectus  Capitis  Anticus  Minor  (m.  rectus  capitis  ante- 
rior); fourth,  the  Rectus  Capitis  Lateralis.  Retract 
forwards  the  Middle  Scalene  (m.  scalenus  medius) 
and  clean  the  Scalenus  Posticus  (m.  scalenus  posterior). 
Look  for  the  Deep  Cervical  Branch  of  the  Superior 
Intercostal  Artery  lying  on  the  Semispinalis  Colli 
Muscle  (w.  semispinalis  cervicis).  In  order  to  fully 
expose  the  Vertebral  Artery  it  would  be  necessary  to 
clip  through  the  costal  processes  and  then  break  away 
the  transverse  processes  of  the  cervical  vertebrae, 
and  if  desired,  this  can  now  be  done. 

SOFT  PALATE 

Open  the  pharynx  posteriorly  in  the  midline,  remove 
all  the  packing,  and  thoroughly  cleanse  its  internal 
surface.  In  opening  the  pharynx  from  behind,  be  on 
the  watch  for  a  pharyngeal  tonsil,  especially  if  the  sub- 


44  DISSECTION  METHODS  AND  GUIDES 

ject  happens  to  be  young.  Make  traction  on  the 
Uvula  in  order  to  tense  the  Levator  Palati  (m.  levator 
veil  palatini).  Remove  the  mucous  membrane  and 
glandular  tissue  from  the  lower  part  of  this  muscle, 
and  expose  the  Azygos  Uvulae  (w.  uvulce)  and  the 
posterior  head  of  the  Palatopharyngeus  (m.  pharyngo- 
palatinus).  Strip  off  the  mucous  membrane  outwards 
and  backwards,  clean  the  Levator  Palati  (m.  levator 
veli  palatini),  and  expose  the  anterior  head  of  the 
Palatopharyngeus  (m.  pharyngopalatinus) .  Explore 
and  then  clean  the  Eustachian  Tube  (tuha  auditiva), 
after  which  slit  it  open. 

Strip  off  the  mucous  membrane  outwards  and  back- 
wards, and  clean  the  Palatopharyngeus  (m.  pharyngo- 
palatinus). Reflect  inwards  the  palatal  attachments  of 
the  Levator  Palati  (m.  levator  veli  palatini)  and  the 
Palatopharyngeus  (m.  pharyngopalatinus),  in  order  to 
expose  the  reflected  tendon  of  the  Tensor  Palati  (m. 
tensor  veli  palatini)  running  around  the  Hamular  Proc- 
ess {hamulus  pterygoideus) . 

Finish  the  removal  of  the  mucous  membrane  from 
the  inner  surface  of  the  pharynx.  Starting  at  the 
Palatopharyngeus  Muscle  (m.  pharyngopalatinus),  strip 
the  mucous  membrane  forwards  to  expose  the  tonsil, 
which  you  should  find  lying  in  the  triangular  interval 
between  the  Palatopharyngeus  (m.  pharyngopalatinus) 
Muscle  (''posterior  pillar")  and  the  Palatoglossus  (w. 
glossopalatinus)  Muscle  (''anterior  pillar").  It  will  be 
best  to  defer  working  out  this  region  until  after  it 
has  been  better  exposed  by  a  longitudinal  section  of 
the  skull. 


TONGUE  45 

NASOPHARYNX 

Saw  through  the  base  of  the  skull  longitudinally 
immediately  to  one  side  of  the  Crista  Galli,  continuing 
the  cut  down  through  the  maxilla  and  hard  palate. 
When  this  has  been  done,  remove  the  entire  septum 
of  the  nose,  scrape  and  thoroughly  cleanse  the  fossae. 
Finish  working  out  the  tonsil  and  the  Palatoglossus 
(m.  glossopalatinus) .  Reflect  the  Inferior  Turbinal 
(concha  nasalis  inferior)  upwards  and  explore  the 
Nasal  Duct  (ductus  nasolacrimalis) .  Reflect  the  Middle 
Turbinal  (concha  nasalis  media)  upwards  and  explore 
the  openings  of  the  Infundibulum  (infundibulum 
ethmoidale)  and  Antrum  of  the  Maxilla  (sinus  maxil- 
laris).  Locate  the  openings  of  the  Sphenoidal  Sinus 
(sinus  sphenoidalis)  and  Posterior  Ethmoidal  Cells 
(cellulcB  ethmoidales) .  It  w411  not  be  necessary  to  cut 
away  or  remove  the  turbinals,  as  they  are  easily 
broken  so  that  they  can  be  turned  up. 

TONGUE 

Saw  through  the  mandible  a  little  to  one  side  of  the 
middle  of  the  symphysis.  On  this  same  side  incise 
the  mucous  membrane  along  and  just  below  the 
outer  border  of  the  tongue,  from  its  base  nearly  to  its 
tip.  Dissect  this  mucous  membrane  outwards  to  the 
mandible.  With  a  pair  of  scissors  sever  the  Mylohyoid 
Muscle  close  to  its  attachment  to  the  mandible,  then 
sever  the  anterior  belly  of  the  Digastric,  and  remove 
the  bone.  Reflect  the  Mylohyoid  Muscle  (m.  mylo- 
hyoideus)  downwards.  Isolate  the  Subhngual  Gland 
(glandula  sublingualis).  Clean  the  deep  anterior  por- 
tion of  the  Submandibular  Gland  (glandula  suhmaxil- 


46  DISSECTION  METHODS  AND  GUIDES 

laris).  Be  careful  not  to  sever  its  (Wharton's) .  Duct 
{ductus  suhmaxillaris) .  Look  for  the  Lingual  or  Gus- 
tatory Nerve  {n,  lingualis)  as  it  crosses  Wharton's 
Duct  {ductus  submaxillaris) .  Just  about  this  point 
look  for  the  anastomotic  branch  to  the  Hypoglossal 
Nerve  {n.  hypoglossus) .  Just  back  of  this,  you  should 
find  several  small  filaments  leading  down  to  the  Sub- 
mandibular Ganglion  {ganglion  submaxillar e) .  Clean 
the  upper  border  of  the  Lingual  Nerve  {n.  lingualis), 
then  clean  its  lower  border  very  carefully  in  order  not 
to  destroy  the  filaments  from  which  depends  the 
Submandibular  Ganglion  {ganglion  submaxillaris). 
Isolate  this  ganglion.  Clean  the  Hypoglossal  Nerve 
{n.  hypoglossus),  being  careful  not  to  sever,  on  its 
upper  border,  its  communication  with  the  Lingual 
{n.  lingualis).  Clean  Wharton's  Duct  {ductus  sub- 
maxillaris) . 

Remove  most  of  the  Submandibular  Gland  {glandula 
submaxillaris).  Only  a  small  portion  of  it  should  be 
allowed  to  remain,  attached  by  its  duct.  This  permits 
free  exposure  of  the  Submandibular  Ganglion  {ganglion 
submaxillaris).  Clean  the  Hyoglossus  Muscle  (m. 
hyoglossus),  carefully  free  its  borders,  and  in  freeing  its 
posterior  border  be  careful  not  to  sever  the  Glosso- 
pharyngeal Nerve  {n.  glossopharyngeus) .  Lift  up  its 
anterior  border  and  free  it  from  the  underlying  struc- 
tures, from  top  to  bottom,  then  sever  it  in  the  middle 
with  a  pair  of  scissors.  Reflect  the  upper  half  of  the 
Hyoglossus  upwards.  Running  around  the  lower  end 
of  the  Stylopharyngeus  you  will  find  the  Glosso- 
pharyngeal Nerve  {n.  glossopharyngeus),  which  then 
runs  under  the  upper  half  of  the  Hyoglossus  Muscle, 


LARYNX  47 

and  should  now  be  traced  out.  Reflect  the  lower  half 
of  the  Hyoglossus  downwards,  and  work  out  the  Lingual 
Artery  (a.  lingualis)  and  its  Dorsalis  Linguae  Branch. 
Clean  the  Lingualis  Inferior  Muscle  (m.  longitudinalis 
linguce  inferior).  Its  fibers  are  longitudinal,  and  you 
will  find  it  close  under  the  tongue  and  hidden  by  the 
upper  part  of  the  Hyoglossus,  combined  with  the 
interlacing  terminal  fibers  of  the  Styloglossus  (m. 
styloglossus).  Clean  the  Geniohyoglossus  Muscle  (m. 
geniohyoglossus) .  Its  fibers  radiate  from  the  upper 
genial  tubercle  of  the  mandible. 

Clean  the  Geniohyoid  Muscle  (m.  geniohyoideus). 
Its  fibers  run  from  the  lower  genial  tubercle  to  the 
Hyoid  Bone,  and  are  parallel  to  the  lowermost  fibers 
of  the  Geniohyoglossus. 

LARYNX 

The  following  muscles,  having  all  been  well  worked 
out  in  previous  dissections,  are  all  to  be  removed  on  the 
left  side:  First,  Digastric  (m.  digastricus) ;  second, 
Mylohyoid  (m.  mylohyoideus) ;  third.  Stylohyoid  (w. 
stylohyoideus) ;  fourth.  Sternohyoid  (m.  sternohyoideus) ; 
fifth.  Sternothyroid  (m.  sternothyreoideus) ;  sixth,  Omo- 
hyoid (m.  omohyoideus) ;  seventh.  Middle  Constrictor 
(m.  constrictor  pharyngis  medius) ;  eighth,  Stylopharyn- 
geus  (m.  stylopharyngeus) . 

Those  on  the  right  side  should  be  retained  as  nearly 
intact  as  may  be  possible.  Isolate  the  Superior  (m. 
laryngeus  superior),  External  {ramus  externus),  and 
Recurrent  (n.  laryngeus  inferior)  Laryngeal  Nerves. 
Clean  the  Cricothyroideus  Muscle,  then  the  Cricothy- 
roid  Membrane.     Clean  the  Thyrohyoideus  Muscle, 


48  DISSECTION  METHODS  AND  GUIDES 

sever  it  close  to  its  lower  attachment,  reflect  it  up- 
wards, and  then  clean  the  outer  surface  of  the  Thyro- 
hyoid Membrane.  Look  for  Parathyroid  Glands  in 
the  recess  behind  the  bar  of  the  hyoid  bone.  Remove 
the  left  half  of  the  thyrohyoid  membrane.  Look  in  the 
larynx  and  note  the  anterior  attachment  of  the  upper 
(false)  Vocal  Cords  (plicce  ventricular es) ;  then  sever  the 
thyroid  cartilage  about  J  inch  to  the  left  of  their 
attachment.  Reflect  the  left  half  of  the  thyroid 
cartilage  downwards,  and,  in  the  following  order,  work 
out:  First,  the  Ary tenoideus ;  second,  Crico-aryten- 
oideus  Posticus;  third,  Crico-ary tenoideus  Lateralis; 
fourth,  the  two  fasciculi  of  the  Thy ro-ary tenoideus. 
Remove  the  pad  of  fat  from  behind  the  Thyrohyoid 
Membrane  and  clean  the  Thyro-epiglottideus  Muscle. 
Trim  away  the  mucous  membrane  and  clean  the  Ary- 
teno-epiglottideus  Muscle. 


THORAX  AND  ABDOMEN 

Order  of  Dissections 

1.  Ischiorectal  Fossa. 

2.  Perineum  Proper  (male). 

3.  Perineum  Proper  (female), 

4.  Thorax  and  its  Contents. 

5.  Abdominal  Wall  and  Inguinal  Hernia. 

6.  Inguinal  and  Femoral  Hernia  from  behind. 

7.  Abdominal  Contents. 

8.  Pelvic  Contents  in  General,  and  Dismemberment  of  Right 
Lower  Extremity. 

9.  Pelvic  Viscera  (male). 

10.  Pelvic  Viscera  (female). 

11.  Spermatic  Cord  and  Testicle. 

12.  Penis  and  Male  Urethra. 

13.  The  Muscles  of  the  Back. 

14.  Spinal  Cord. 

ISCHIORECTAL  FOSSA 

Take  a  2-yard  length  of  strong,  thick  twine  and  tie 
it  in  a  loop.  Securely  fasten  a  plug  of  tow,  oakum,  or 
some  such  material  in  one  end  of  this  loop.  Thrust 
this  plug  far  into  the  rectum,  allowing  the  other  end 
of  the  loop  to  protrude.  Later  on  you  will  find  that 
by  pulling  on  this  loop  you  can  make  structures  con- 
veniently superficial  which  otherwise  would  be  hard 
to  reach.  The  rectum  and  vagina  should  be  packed 
tightly.  The  anus  and  vulva  should  be  sewn  shut. 
The  body  should  now  be  placed  on  its  belly  and  drawn 

4  49 


60  DISSECTION  METHODS  AND  GUIDES 

across  the  table,  or  to  the  lower  end  of  the  table,  allow- 
ing the  legs  to  hang  down.  From  the  tip  of  the  coccyx, 
make  an  incision  downwards  and  outwards  to  a  point 
just  over  the  insertion  of  the  Gluteus  Maximus  (m. 
glutceus  maximus),  below  the  Great  Trochanter  {tro- 
chanter major)  of  the  femur.  Cut  down  to  the  Gluteus 
Maximus  Muscle  (m.  glutceus  maximus)  and  thoroughly 
clean  and  expose  its  postero-inferior  border.  With 
a  pair  of  blunt-pointed  scissors  (''curved  on  the  flat") 
dissect  the  skin  up  to  the  margin  of  the  anus,  trim  it 
around  the  margin  of  the  anus,  dissect  it  off  the  peri- 
neum, cut  it  off  transversely,  and  get  rid  of  it.  Do  not 
attempt  to  remove  any  of  the  underlying  fat  while 
dissecting  off  the  skin. 

Lift  up  the  postero-inferior  border  of  the  Gluteus 
Maximus  Muscle  (m.  glutceus  maximus)  and  look  for 
the  Long  (Inferior)  Pudendal  Nerve  (n.  pudendus 
inferior).  You  should  find  it  crossing  the  tendinous 
origin  of  the  Biceps  Muscle  (m.  biceps  femoris) ,  at  right 
angles,  about  2  inches  below  the  tuberosity  of  the 
ischium.  Do  not  attempt  to  trace  out  this  nerve  until 
the  body  is  placed  in  the  lithotomy  position.  Just 
locate  it  definitely  and  remember  where  it  is  when 
you  come  to  the  removal  of  the  overlying  fat.  Care- 
fully clean  away  the  fat  from  over  the  External 
Sphincter  'Ani  Muscle  (m.  sphincter  ani  externus). 
Begin  at  the  tip  of  the  coccyx  and  follow  the  muscle- 
fibers  forwards  around  the  anus  to  their  insertion  in  the 
fibrous  central  tendon  of  the  perineum.  Locate  and 
clean  the  Great  Sacrosciatic  Ligament  (l.  sacrotuhero- 
sum),  but  do  not  sever  it.  Emerging  from  underneath 
this  ligament  and  running  toward  the  anus  you  will 


ISCHIORECTAL  FOSSA 


51 


-77^  of  CoceyK 


Insertion  of  ' 
Gluteus  ma  aim  us 


Inserf'ion  of 
Gluteus  max/ mas 


Insert  ion    of,  ^' 
6 lute  us  maximus 


Fig.  3. — Ischiorectal  Fossa  and  Perineum. 

Continuous  red  lines  indicate  knife   incisions.     Red   dotted   lines   indicate 

where  the  skin  should  be  cut  with  scissors. 


52  DISSECTION  METHODS  AND  GUIDES 

find  the  External  (Inferior)  Hemorrhoidal  (a.  hcemorrhoi- 
dalis  inferior)  Branch  of  the  Internal  Pudic  (a.  pudenda 
interna)  Artery,  and  with  it  the  Inferior  Hemorrhoidal 
(n,  hcemorrhoidalis  inferior)  Branch  of  the  Pudic  Nerve 
(n.  pudendus).  These  should  be  cleaned  and  freed. 
In  the  front  part  of  the  ischiorectal  fossa  look  for  the 
External  (or  Posterior)  Superficial  Perineal  (n.  perinei) 
Branch  of  the  Pudic  Nerve  (n.  pudendus).  Clean  it  as 
far  as  the  posterior  margin  of  the  Triangular  Ligament 
{diaphragma  urogenitale) .  Remove  all  the  fat  from  the 
ischiorectal  fossa,  except  from  its  anterior  extension. 
Clean  the  Levator  Ani  Muscle. 

PERINEUM  PROPER   (MALE) 

Place  the  body  on  its  back  and  secure  it  in  the 
Uthotomy  position.  Dissect  the  skin  forwards,  splitting 
it  in  the  midline  as  you  progress.  Reflect  it  outwards 
as  far  as  the  genitocrural  crease,  and  cut  it  away,  along 
the  crease.  Work  out  the  Long  Pudendal  Nerve  (n. 
pudendus  inferior),  then  entirely  remove  the  superficial 
thick  fatty  layer  of  the  superficial  fascia  in  order  to  ex- 
pose CoUes'  Fascia,  which  is  the  thin  fibrous  layer  of  the 
superficial  fascia.  Beginning  on  each  side,  close  to  the 
ischial  tuberosity,  detach  CoUes'  Fascia  from  the  outer 
lip  of  the  lower  margin  of  the  ischiopubic  ramus,  going 
as  far  forwards  as  is  convenient.  Detach  it  posteriorly 
from  the  transverse  perineal  margin  of  the  Triangular 
Ligament  {diaphragma  urogenitale),  and  reflect  it  for- 
wards. This  opens  up  the  Superficial  Perineal  Inter- 
space, which,  you  will  note,  is  the  interval  between 
CoUes'  Fascia  and  the  superficial  (inferior)  layer  of  the 
Triangular  Ligament  {fascia  diaphragmatis  urogenitalis 


PERINEUM  PROPER  (MALE)  53 

inferior).  You  will  find  in  it  the  following  structures: 
On  each  side,  the  Corpus  Cavernosum,  surrounded  by 
the  Ischiocavernosus  (Erector  Penis)  Muscle.  In  the 
midline,  the  Bulb  of  the  Corpus  Spongiosum,  surrounded 
by  the  Bulbocavernosus  (Accelerator  Urinse)  Muscle. 
In  the  back  part,  close  to  the  free  border  of  the  Tri- 
angular Ligament,  the  Superficial  Transversus  Peri- 
nsei  Muscle.  Lastly,  piercing  this  muscle  or  crossing 
it  from  behind  forwards,  you  will  find  the  superficial 
perineal  vessels  and  nerves.  Clean  all  the  structures 
in  this  space  in  the  order  in  which  they  have  just  been 
given  and  remove  all  of  the  fat.  Detach  both  crura 
of  the  Corpora  Cavernosa  close  to  the  bone,  then 
divide  the  urethra  close  to  the  surface  of  the  triangular 
ligament.  Reflect  forwards  the  bulb  and  the  Corpora 
Cavernosa  in  order  to  fully  expose  the  surface  of  the 
Superficial  Layer  (fascia  diaphragmatis  urogenitalis 
inferior)  of  the  Triangular  Ligament. 

Divide  this  superficial  layer  on  each  side,  just 
internal  to  and  close  to  the  former  attachment  of  the 
crus  of  the  Corpus  Cavernosum.  Reflect  each  half 
toward  the  midline.  As  you  progress,  sever  its  attach- 
ment to  the  free  margin  of  the  deep  layer. 

This  opens  up  the  Deep  Perineal  Interspace,  which, 
you  will  note,  is  the  interval  between  the  Superficial 
Layer  and  the  Deep  Layer  (fascia  diaphragmatis 
urogenitalis  superior)  of  the  Triangular  Ligament. 
In  this  space,  in  the  midline,  look  for  and  clean  the 
Membranous  Urethra.  On  each  side,  close  behind 
the  urethra,  look  for  Cowper's  Glands  and  isolate  them. 
Clean  the  Deep  Transverse  Perineal  (transversus  peri- 
nod  profundus)  Muscle  (also  called  compressor  urethrce). 


64  DISSECTION  METHODS  AND  GUIDES 

Piercing  this  muscle  near  its  osseous  attachment  on 
each  side,  are  the  Internal  Pudic  (or  pudendal)  Vessels 
and  Nerve,  which  should  now  be  cleaned.  Now  re- 
move all  the  fat  from  this  area  and  clean  the  surface 
of  the  Deep  (Superior)  Layer  of  the  Triangular  Liga- 
ment. Incise  the  deep  triangular  ligament  on  one  side 
in  order  to  open  up  the  Anterior  Extension  of  the 
Ischiorectal  Fossa.  Remove  all  the  fat  from  this 
region,  and  then,  follow  backwards  the  Internal  Pudic 
Artery  and  Nerve  into  Alcock's  Canal.  SUt  this  canal 
open  in  order  to  expose  it  fully. 

Alcock's  Canal  is  formed  by  the  lower  part  of  the 
ischiorectal  portion  of  the  Obturator  Fascia.  It  is 
about  1  inch  above  the  level  of  the  margin  of  the 
tuberosity  of  the  ischium. 

PERINEUM   PROPER   (FEMALE) 

Place  the  body  on  its  bac*k  and  secure  it  in  the 
lithotomy  position.  On  both  sides,  make  a  skin  inci- 
sion in  the  Genitocrural  Crease,  continue  both  inci- 
sions forwards,  and  then  curve  them  so  that  they  will 
meet  above  the  Mons  Veneris  and  include  it.  Dissect 
the  skin  toward  the  midline  as  far  as  the  margin  of  the 
vulva,  then  trim  it  away  from  the  margin  of  the  vulva 
with  a  pair  of  scissors.  Do  not  attempt  to  remove  any 
of  the  underlying  fat  with  the  skin.  Pick  up  the  Long 
Pudendal  Nerve  (n.  pudendus  externus)  and  trace  it 
out.  Beginning  in  the  Genitocrural  Crease,  cut  care- 
fully through  the  thick  superficial  fatty  layer  of  the 
superficial  fascia  until  you  reach  the  thin  fibrous  layer 
of  the  superficial  fascia.  In  the  perineum,  this  fibrous 
layer  is  known  as  CoUes'  Fascia.    It  becomes  very  thin 


PERINEUM  PROPER  (FEMALE)  55 

toward  the  midline.  Reflect  the  fatty  layer  inwards, 
toward  the  midline,  following  the  plane  of  CoUes'  Fascia 
until  you  reach  the  margin  of  the  vulva,  then  trim  it 
away  with  scissors. 

Be  very  cautious  not  to  cut  away  CoUes'  Fascia, 
especially  as  you  approach  the  midline.  Detach 
CoUes'  Fascia  from  the  ischial  tuberosity  and  along 
the  outer  lip  of  the  lower  margin  of  the  ischiopubic 
ramus,  and  reflect  it  toward  the  midline.  As  you 
progress,  detach  it  posteriorly  from  the  free  border 
of  the  triangular  Hgament,  and  remove  it  as  you  did 
the  fatty  layer. 

This  opens  up  the  Superficial  Perineal  Interspace, 
which  is  the  interval  between  the  Colles'  Fascia  and 
the  Superficial  (Inferior)  Layer  of  the  Triangular  Liga- 
ment. The  triangular  Ugament  and  perineal  inter- 
spaces are  necessarily  much  smaller  in  the  female 
than  in  the  male,  on  account  of  their  being  traversed 
by  the  vagina.  Most  of  the  analogous  structures  are 
much  smaller  and  less  well  defined  in  the  female  than 
in  the  male.  In  the  Superficial  Perineal  Interspace, 
on  each  side,  you  will  find  the  Crus  Cavernosum  (cms 
clitoridis),  covered  by  the  Ischiocavernosus  Muscle. 
Free  it  from  fat.  Near  the  free  margin  of  the  triangu- 
lar ligament  you  should  find  the  Superficial  Transverse 
Perineal  Muscle.  Usually  it  is  small  and  indistinct. 
Crossing  this  muscle  or  piercing  it  from  behind  for- 
wards are  the  Superficial  and  Transverse  Perineal 
Vessels  and  Nerves.  These  should  be  carefully  traced 
out.  In  each  Labium  Majus,  you  will  find  the  Bulbus 
Vestibuli  covered  by  the  Bulbocavernosus  (constrictor 
vagince)    Muscle.     Clean   this  muscle,   working  from 


66  DISSECTION  METHODS  AND  GUIDES 

behind  forwards.  Free  the  outer  edge  of  the  Bulbo- 
cavernous Muscle  and  lift  it  up. 

Lying  underneath  it,  at  the  back  part,  is  the  Gland 
of  Bartholin  (glandula  vestibularis  major),  and  from 
there  forwards  you  will  find  a  tangled  mass  of  blood- 
vessels, forming  the  Bulbus  Vestibuli.  Having  iso- 
lated the  foregoing  structures,  remove  all  the  fat  from 
this  area  and  expose  the  Superficial  Layer  of  the 
Triangular  Ligament.  Incise  this  layer  along  and  just 
internal  to  the  Crus  Clitoridis.  This  opens  up  the 
Deep  Perineal  Interspace,  which  is  the  interval  be- 
tween the  Superficial  Layer  and  the  Deep  Layer  of 
the  Triangular  Ligament. 

Putting  a  sound  into  the  urethra  will  enable  you  to 
easily  locate  and  clean  its  outer  surface.  Running 
outwards  from  in  front  of  the  urethra,  you  will  find  the 
Transversus  Perinsei  Profundus  (compressor  urethrce) 
Muscle.  Close  to  the  margin  of  the  Ischiopubic  Ra- 
mus, look  for  the  Internal  Pudic  (a.  pudenda  interna) 
Artery  and  Nerve  (n.  pudendus) .  Trace  them  forwards. 
Remove  all  the  fat  from  this  region  and  expose  the 
Deep  (Superior)  Layer  of  the  Triangular  Ligament. 
Incise  this  deep  layer  and  open  up  the  Anterior  Ex- 
tension of  the  Ischiorectal  Fossa.  Pick  up  the  Inter- 
nal Pudic  {a.  pudenda  interna)  Artery  and  Nerve  (n. 
pudendus)  and  follow  them  backwards  through  Alcock's 
Canal,  slitting  the  canal  open  as  you  go.  This  canal  has 
already  been  explained  in  connection  with  the  male  peri- 
neum {q.  v.). 

THORAX  AND  ITS  CONTENTS 

Detach  the  Pectoral  Muscles  from  the  ribs.  Divide 
the  sternum  transversely,  immediately  below  the  level 


THORAX  AND  ITS  CONTENTS  57 

of  the  first  pair  of  costal  cartilages.  It  will  be  better 
to  saw  only  part  way  through  the  bone  and  then  to 
complete  the  saw-cut  with  bone-forceps  or  a  sharp 
flat  chisel.  On  each  side  extend  this  cut  laterally, 
through  intercostal  muscles  and  pleura,  as  far  as  the 
anterior  axillary  line.  Take  a  costotome  and  divide 
the  second  rib  where  it  is  crossed  by  the  anterior 
axillary  line;  continue  downwards  in  this  line,  dividing 
the  pleura,  intercostal  muscles,  and  ribs  until  you  have 
cut  the  eighth  rib  or  until  you  reach  the  diaphragm. 
It  may  be  necessary  to  cut  the  ninth  rib  and  some- 
times even  the  tenth,  but  in  any  event,  avoid  cutting 
through  the  diaphragm.  Therefore,  as  this  procedure 
is  to  be  carried  out  on  both  sides,  it  will  be  safer  not  to 
sever  the  lowermost  ribs  until  after  lifting  up  the 
sternum.  Lift  up  the  lower  portion  of  the  sternum 
and  detach  the  underlying  pleurae,  superior  sterno- 
pericardial band,  and  areolar  tissue  from  its  poste- 
rior surface. 

This  large  sternocostal  flap  is  to  be  bent  down  until 
it  lies  flat  on  the  belly,  and  it  should  be  secured  there 
by  a  belt  of  twine.  While  doing  this,  it  will  be  easy 
to  determine  how  many  of  the  lower  ribs  need  to  be  cut. 
On  the  posterior  surface  of  this  flap,  you  can  study  the 
Internal  Mammary  Arteries,  the  Triangulares  Sterni 
Muscles,  and  the  Lower  Sternopericardial  Band. 

Fold  the  skin  of  the  chest  over  the  cut  ends  of  the 
ribs  and  sew  it  fast  in  this  position,  in  order  to  protect 
your  hands  from  the  sharp  ends  of  the  ribs.  Do  not 
remove  any  of  the  organs  from  the  chest.  It  is  im- 
perative that  every  one  of  them  be  retained  in  its 
natural  position.     Do  not  open  the  Pericardium.     If 


58  DISSECTION  METHODS  AND  GUIDES 

it  has  been  opened  accidentally,  then  sew  up  that 
opening  before  proceeding  any  further.  You  now  have 
before  you,  widely  open,  both  of  the  pleural  cavities, 
the  Superior  Mediastinum  and  the  Anterior  Medi- 
astinum (or  Interpleural  Space),  which  should  now  be 
studied. 

The  Phrenic  Nerves  (nn.  phrenici)  should  now  be 
Ufted  up  and  cleaned.  Each  of  them  will  be  found 
crossing  in  front  of  the  "root"  of  the  lung  and  running 
downwards,  between  the  pleur^  and  the  pericardium, 
or  on  the  front  of  the  pericardium,  to  reach  the  dia- 
phragm. The  Right  Phrenic  pierces  the  diaphragm 
immediately  to  the  left  of  the  opening  (foramen  vence 
cavce)  for  the  Inferior  Vena  Cava  (post  cava) .  The  Left 
Phrenic  pierces  the  diaphragm  immediately  to  the  left 
of  the  attachnient  of  the  pleura  and  diaphragm  to 
each  other.  You  should  now  find  the  Pneumogastric 
(nn.  vagi)  Nerves,  so  that  you  will  know  where  they 
are,  in  order  to  avoid  injuring  them.  Do  not  try  to 
work  them  out  as  yet,  simply  identify  them. 

You  will  find  the  Left  Pneumogastric  Nerve  (n. 
vagus  sinister)  running  downwards,  crossing  in  front  of 
the  Arch  of  the  Aorta  (arcus  aortce),  and  then  passing 
behind  the  root  of  the  left  lung. 

The  Right  Vagus  (n.  vagus  dexter)  is  much  more 
deeply  situated  than  the  left.  You  will  find  it  em- 
bedded in  the  loose  areolar  tissue  on  the  right  side 
of  the  trachea.  It  runs  downwards  behind  the  root  of 
the  right  lung. 

Free  the  right  lung  from  any  pleural  adhesions  there 
may  be.  Put  your  hand  down  under  it,  lift  it  up  out  of 
the  chest,  and  turn  it  over  to  the  left  as  far  as  you  can. 


THORAX  AND  ITS  CONTENTS  59 

With  the  right  lung  out  in  this  position,  look  for  the 
Vena  Azygos  Major  {v.  azygos).  You  will  find  it 
running  upwards  along  the  sides  of  the  bodies  of  the 
vertebrae. 

Tear  through  the  pleura  just  to  the  left  of  the 
Azygos  Vein  and  look  for  the  Thoracic  Duct  {ductus 
thoracicus).  You  will  find  it  lying  in  the  loose  areolar 
tissue  between  the  Azygos  Vein  and  the  Aorta.  It  is 
brownish-red  in  color  and  looks  like  a  small,  lumpy, 
thin-walled  vein.  The  Right  Intercostal  Arteries  {aa. 
inter costales)  are  immediately  behind  it  and  run  at 
right  angles  to  it.  Replace  the  right  lung,  and  then 
carry  out  the  following  steps  in  exactly  the  following 
order : 

1.  Trace  out  and  clean  the  Left  Pneumogastric 
Nerve  (n.  vagus  sinister).  You  will  find  it  running 
downwards  in  front  of  the  Arch  of  the  Aorta  {areas 
aortce),  behind  the  root  of  the  left  lung,  in  close  con- 
tact with  the  back  of  the  bronchus,  on  the  front  of 
the  esophagus,  to  the  Plexus  Guise  {esophageal  plexus), 
and  from  thence  through  the  esophageal  opening  of  the 
diaphragm.  Be  careful  not  to  divide  its  pulmonary 
branches  behind  the  bronchus  or  its  communicating 
branches.    Again  Hft  out  the  right  lung. 

2.  Clean  the  Vena  Azygos  Major  {v.  azygos).  Begin 
between  the  crura  of  the  diaphragm  and  follow  it  up 
the  sides  of  the  vertebra,  behind  the  root  of  the  right 
lung,  then,  curUng  around  the  root  of  the  lung  in  con- 
tact with  the  right  bronchus  and  Pneumogastric 
{n.  vagus),  to  the  Superior  Vena  Cava  {precava). 

3.  Trace  the  Thoracic  Duct  {ductus  thoracicus)  from 
the  Aortic  Opening  {hiatus  aorticus)  of  the  diaphragm 


60  DISSECTION  METHODS  AND  GUIDES 

upwards  along  the  right  side  of  the  aorta  in  the  Poste- 
rior Mediastinum  (interpleural  space),  to  where,  at 
about  the  level  of  the  fifth  thoracic  vertebra,  it  passes 
behind  the  aortic  arch  and  the  esophagus  into  the 
Superior  Mediastinum  (interpleural  space).  It  is  very 
easily  torn,  so  you  must  be  cautious  in  handling  it. 

4.  Trace  out  and  clean  the  Right  Pneumogastric 
Nerve  (n.  vagus  dexter).  You  will  find  it  behind  the 
Right  Innominate  Vein  (v.  anonyma  dextra),  running 
downwards  along  the  right  side  of  the  trachea,  behind 
the  root  of  the  right  lung,  where  it  becomes  broad 
and  flat  and  forms  two  cords,  downwards  behind  the 
esophagus,  where  the  two  cords  coalesce  and  con- 
tinue, as  one,  through  the  Esophageal  Opening  (hyatus 
oesophageus)  of  the  Diaphragm. 

5.  Lift  out  the  left  lung  and  clean  the  Vena  Azygos 
Minor  (v.  hemiazygos),  from  the  left  crus  of  the  dia- 
phragm to  where  it  crosses  the  eighth  or  ninth  vertebra 
to  join  the  Azygos  Major.     Clean  the  esophagus. 

6.  Push  the  esophagus  towards  the  right,  and  finish 
tracing  the  Thoracic  Duct  through  the  Superior 
Mediastinum  as  far  as  the  upper  opening  of  the  tho- 
rax.    Be  careful  not  to  tear  it  in  two. 

7.  Clean  the  Superior  Vena  Cava  (precava) ;  be  care- 
ful not  to  cut  the  Azygos  Major,  entering  it  from  be- 
hind or  on  its  outer  side.  Clean  the  Right  Innominate 
Vein  (v.  anonyma  dextra);  be  careful  of  the  Inferior 
Thyroid  (v.  thyreoidea  inferior),  entering  it  on  the  inner 
side. 

Clean  the  Left  Innominate  Vein  (v.  anonyma  sinis- 
tra). Be  careful  of  the  Inferior  Thyroids  (vv.  thyreoidece 
inferiores)  entering  it  from  above,  and  the  Superior 


THORAX  AND  ITS  CONTENTS  61 

Intercostal  {v.  intercostalis  suprema  sinistra)  entering 
it  from  below. 

Clean  the  Left  Superior  Intercostal,  tracing  it  down 
to  the  Vena  Azygos  Tertia  (v.  hemiazygos  accessoria). 

8.  Clean  the  outer  surface  of  the  Pericardium. 
Follow  up  its  tubular  prolongation  surrounding  the 
Pulmonary  Artery  (a.  pulmonalis)  and  Aorta. 

In  front  of  it  (Anterior  Mediastinum)  look  for  the 
Thymus  Gland  or  its  remains. 

9.  Open  the  Pericardium  widely  from  in  front. 
Study  its  interior  (Middle  Mediastinum)  and  note 
the  reflections  of  its  serous  layer  on  to  the  great  vessels. 
Take  a  blunt-pointed  pair  of  scissors  and  split  the 
Pericardium  up  to  each  of  the  great  blood-vessels  and 
trun  it  away  from  around  each  of  them.  Be  especially 
careful  not  to  injure  the  Inferior  Vena  Cava  (postcava) 
when  freeing  it.  It  is  safer  to  leave  intact  that  portion 
of  the  pericardium  which  is  attached  to  the  left  border 
of  its  opening  in  the  diaphragm,  along  with  the  por- 
tion that  is  attached  to  the  upper  surface  of  the  dia- 
phragm. Otherwise,  remove  all  of  the  pericardium. 
Do  not  remove  the  heart  and  do  not  cut  it  open. 
It  must  be  kept  intact  and  in  place.  Use  another 
specimen  for  comparison  and  for  the  study  of  the 
interior  of  the  heart. 

10.  Remove  the  pleura  from  the  root  of  each  lung. 
Isolate  and  thoroughly  clean  this  portion  of — first,  the 
Pulmonary  Vein  (v.  pulmonalis) ;  second,  just  above  it 
the  Pulmonary  Artery  (a.  pulmonalis);  third,  above 
the  vein  and  behind  the  artery,  the  Bronchus.  Only 
clean  up  as  much  of  these  as  you  find  entering  into  the 
formation  of  the  ''root"  of  the  lung. 


62  DISSECTION  METHODS  AND  GUIDES 

11.  Clean  the  Arch  of  the  Aorta.  In  doing  so  rotate 
and  reflect  it  towards  the  left.  Clean  the  Ductus 
Arteriosus  {ligamentum  arteriosum) ;  divide  it  in  the 
middle,  but  pass  a  stitch  of  strong,  heavy  thread 
through  both  of  the  divided  ends  and  tie  it  in  a  large 
loop.  Later  this  will  serve  to  draw  and  tie  them  to- 
gether  again;  in  the  meantime  it  gives  you  far  more 
room  to  work,  and  saves  much  time  and  trouble. 
Clean  the  upper  part  of  the  Thoracic  Aorta. 

12.  Isolate  the  Left  Recurrent  Laryngeal  Nerve 
(n.  laryngeus  inferior  sinister).  Follow  it  under  the 
Arch  of  the  Aorta;  then  upwards  and  obliquely  in- 
wards, behind  the  Aorta  and  the  Left  Common 
Carotid  Artery  (a.  carotis  communis  sinistra),  to  the 
angular  groove  between  the  esophagus  and  trachea. 

13.  Finish  cleaning  the  Pulmonary  Veins  {vv.  pul- 
monales)  and  the  Pulmonary  Arteries  {aa.  pulmonales). 

14.  Clean  the  Innominate  Artery  (a.  anonyma). 
Clean  the  Left  Common  Carotid  (a.  carotis  communis 
sinistra)  and  Left  Subclavian  (a.  subclavia  sinistra) 
Arteries  as  far  as  the  upper  opening  of  the  thorax. 

15.  Clean  the  Trachea  and  finish  cleaning  the  Bronchi. 

16.  Clean  the  lower  part  of  the  Thoracic  Aorta. 

17.  Look  on  the  front  of  the  heads  of  the  ribs  for  the 
ganglia  of  the  Gangliated  Cord  (truncus  sympatheticus) . 
They  are  rather  white  in  color  and  are  covered  only 
by  pleura.  Trace  the  cords  of  the  Sympathetic  from 
above  downwards. 

18.  Restore  the  severed  Ductus  Arteriosus.  When 
you  tie  its  ends  together,  make  sure  that  you  leave  the 
Recurrent  Laryngeal  Nerve  to  the  left  of  the  Ductus 
Arteriosus. 


THORAX  AND  ITS  CONTENTS 


63 


Fig.  4. — Thorax  and  Abdomen. 

Continuous  red  lines  indicate  knife  incisions.     Dotted  red  lines  show  where 

the  skin  should  be  cut  with  scissors. 


64  DISSECTION  METHODS  AND  GUIDES 

19.  Divide  the  upper  piece  of  the  sternum  in  the  mid- 
line. Saw  the  clavicles  in  the  middle,  and  saw  the  first 
pair  of  ribs  immediately  anterior  to  the  groove  for  the 
Subclavian  Vein.    Take  care  not  to  injure  the  vein. 

ABDOMINAL  WALL  AND  INGTHNAL  HERNIA.     (See  Fig.  4.) 

Make  a  skin  incision  in  the  midline  of  the  abdomen, 
extending  from  the  ensiform  process  (xiphoid  cartilage) 
to  the  symphysis  pubis,  encircling  the  umbilicus. 
Reflect  the  skin  laterally  as  far  as  the  anterior  border 
of  the  Latissimus  Dorsi  Muscle.  Do  not  make  any 
knife  incision  along  the  line  of  Poupart's  Ligament 
(1.  inguinale),  but  when  the  skin  has  been  dissected  as 
far  down  as  that,  cut  it  with  scissors  from  the  sym- 
physis along  the  line  of  Poupart's  Ligament  (I.  ingui- 
nale), then  following  the  crest  of  the  ilium  to  the 
border  of  the  Latissimus  Dorsi.  Begin  in  the  midline 
by  cutting  cautiously  through  the  layer  of  fat,  and  by 
reflecting  it  laterally  expose  the  Linea  Alba.  Con- 
tinue reflecting  the  fatty  layer  outwards  until  you  have 
exposed  the  sheath  of  the  Rectus  Abdominis  and  the 
Linese  Transversse. 

Now  look  for  the  Anterior  Cutaneous  Nerves  which 
pierce  the  sheath  of  the  rectus,  at  regular  intervals, 
close  to  its  outer  border.  There  are  five  pairs  of  them. 
Below  these,  preserving  the  same  interval,  you  will 
find  the  Iliohypogastric  Nerve,  and  below  it,  the 
Ilio-inguinal  Nerve  as  it  emerges  from  the  External 
(Superficial)  Abdominal  Ring  {annulus  inguinalis  sub- 
cutaneous) .  Reflect  the  fatty  layer  outwards  only  as  far 
as  will  permit  of  your  cleaning  the  Linea  Semilunaris. 
Look   for   the   Superficial   Epigastric   Branch   of   the 


ABDOMINAL  WALL  AND  INGUINAL  HERNIA  65 

Femoral  Artery,  running  upwards  across  the  middle  of 
Poupart's  Ligament  {I.  inguinale) .  Plough  through  the 
fat  along  the  course  of  this  artery  and  isolate  it  from 
the  surrounding  fat.  Clean  the  anterior  border  of  the 
Latissimus  Dorsi  Muscle  in  the  lumbar  region.  Reflect 
the  fatty  layer  forwards,  exposing  the  Lumbar  Fascia 
and  the  posterior  border  of  the  Obliquus  Extemus 
Muscle  (Triangle  of  Petit).  Look  for  the  Lateral 
Cutaneous  Nerves;  they  run  forwards  after  emerging, 
at  regular  intervals,  from  between  the  digitations  of 
the  Serratus  Magnus  (m.  serratus  anterior)  and  the 
Lumbar  Fascia.  Now  remove  all  of  the  fat  and  clean 
the  entire  extent  of  the  External  Oblique  Muscle 
(m.  obliquus  extemus  abdominis).  Clean  the  Inter- 
columnar  Fibers  (fibrce  intercrurales)  and  Fascia,  the 
Internal  (Superior)  Pillar  {crus  superius),  the  External 
(Inferior)  Pillar  {crus  infirius),  and  clearly  define  the 
External  (Superficial)  Abdominal  Ring  (annulus  in- 
guinalis  subcutaneous) . 

Split  lengthwise,  along  its  midline,  the  fascia  forming 
the  anterior  lamella  of  the  sheath  of  the  Rectus  Ab- 
dominis Muscle .  At  the  lower  end ,  clean  the  Pyramidalis 
Muscle.  Free  the  Rectus  Muscle,  lift  up  its  outer  border, 
and  trace  up  the  Deep  Epigastric  (a.  epigastrica  inferior) 
Branch  of  the  External  Iliac  Artery  {iliaca  externa). 

Return  to  the  Triangle  of  Petit  and  free  the  poste- 
rior border  of  the  External  Oblique  (m.  obliquus  ex- 
temus abdominis)  from  the  lumbar  fascia;  thrust  your 
finger  under  and  free  it  from  the  underlying  Internal 
Oblique  (m.  obliquus  intemus  abdominis).  As  you 
progress  forwards,  divide  the  External  Oblique,  with 
scissors,  until  you  attain  the  Linea  Semilunaris.     In 

5 


66  DISSECTION  METHODS  AND  GUIDES 

the  same  way  lift  it  up  and  divide  it  along  the  Linea 
Semilunaris,  reflecting  the  upper  portion  upwards  and 
outwards,  and  the  lower  portion  downwards  and  out- 
wards. Be  careful  not  to  divide  the  Inner .  Column 
{cms  superius)  of  the  External  Abdominal  Ring 
{annulus  inguinalis  subcutaneous).  Clean  the  Ob- 
hquus  Internus  Muscle,  and  divide  it  on  a  line  parallel 
to  and  about  3  inches  external  to  the  Linea  Semi- 
lunaris. Begin  above,  where  the  separation  is  easily 
made,  and  cut  cautiously  through  the  muscular 
fibers;  separate  them  with  your  knife  handle  from  the 
underlying  TransversaHs  (m.  transversus  abdominis); 
continue  downwards  until  you  can  no  longer  effect 
any  separation.  You  will  then  have  reached  the 
Conjoint  Tendon.  Remove  the  Lumbar  Fascia  and 
clean  the  Quadratus  Lumborum  Muscle.  Reflect  the 
outer  portion  of  the  Internal  Oblique  outwards  and 
expose  the  TransversaHs.  Do  not  interfere  with  the 
Spermatic  Cord  (or  Round  Ligament)  otherwise  than 
to  fully  expose  it  in  the  Inguinal  Canal.  You  now  have 
before  you  the  parts  involved  in  Inguinal  Hernia,  as 
seen  from  in  front. 

INGUINAL  AND  FEMORAL  HERNIA  FROM  BEHIND 

In  order  to  study  this  region  from  behind,  the  abdomi- 
nal wall  should  be  divided  transversely  above  the  level 
of  anterior  superior  spines  of  the  ilia.  Having  done 
this,  inspect  the  peritoneal  surface  of  the  lower,  portion 
(note  the  position  of  the  Urachus  in  the  midline)  and 
divide  it  along  the  right  side  of  the  urachus  down  to 
the  Symphysis  Pubis.  Reflect  each  side  downwards 
and  outwards  and  study  its  peritoneal  surface.      On 


INGUINAL  AND  FEMORAL  HERNIA  FROM  BEHIND       67 

one  of  the  flaps  you  will  see  the  Urachus,  forming  the 
so-called  Median  Cord. 

Immediately  external  to  the  Urachus,  and  lying 
between  it  and  the  obliterated  Hypogastric  Artery 
(ligamentum  umhilicale  laterale),  is  the  Internal  Peri- 
toneal Fossa.  This  fossa  is  directly  behind  the  Exter- 
nal Abdominal  Ring  {annulus  inguinalis  subcutaneous) , 
and  it  is  here  that  a  direct  hernia  takes  place. 

Between  the  Obliterated  Hypogastric  Artery  {liga- 
mentum umhilicale  laterale)  and  the  Deep  Epigastric 
Artery  (a.  epigastrica  inferior)  is  the  Middle  Peritoneal 
Fossa.  It  corresponds  to  the  posterior  wall  of  the 
Inguinal  Canal.  It  is  not  the  seat  of  hernia  and  is 
likely  to  be  entirely  obliterated  by  an  oblique  hernia, 
and  also  by  a  large  direct  hernia. 

Just  external  to  the  Deep  Epigastric  Artery  (a.  epi- 
gastrica inferior)  is  the  External  Peritoneal  Fossa. 
This  corresponds  to  the  Internal  Abdominal  Ring 
(annulus  inguinalis  abdominis),  and  this  is  the  part 
which  is  ruptured  when  an  oblique  hernia  enters  the 
inguinal  canal.  An  oblique  hernia  may  so  distend  the 
internal  abdominal  ring  that  the  inguinal  canal  may 
no  longer  exist  as  a  canal,  and  the  internal  ring  will 
then  coincide  with  the  external  ring,  which  will  also 
be  distended.  You  can  now  understand  why  the 
Deep  Epigastric  Artery  (a.  epigastrica  inferior)  is 
always  to  the  inner  side  of  an  oblique  hernia,  and  to 
the  outer  side  of  a  direct  inguinal  hernia.  Therefore 
the  displacement  of  this  artery  is  important  surgically. 
Note  the  position  of  Poupart's  Ligament  (/.  inguinale). 

Note  the  Femoral  Fossa  just  below  the  ligament 
and  internal  to  the  Iliac  Vessels  as  they  pass  under 


68  DISSECTION  METHODS  AND  GUIDES 

the  ligament.  Thrusting  the  bladder  out  of  the  way, 
you  should  be  able  to  feel  the  inner  opening  of  the 
Obturator  Canal.  Strip  the  peritoneum  away  from  the 
abdominal  flaps  and  expose  the  Urachus,  posterior 
surface  of  the  Rectus  Muscle,  Obliterated  Hypogastric 
Artery,  and  posterior  surface  of  the  Conjoint  Tendon 
(floor  of  Hesselbach's  Triangle). 

Carefully  clean  the  Deep  Epigastric  Artery  and  the 
Internal  Abdominal  Ring.  Follow  the  Transversalis 
Fascia  into  the  ring.  Isolate  the  Vas  Deferens  (ductus 
deferens)  or  Round  Ligament  (l.  teres  uteri),  entering 
the  internal  ring  from  below,  and  the  Spermatic 
Vessels  (vasce  spermaticce  internee),  entering  the  ring 
on  its  outer  side.  Note  that  the  Spermatic  Cord  is 
formed  in  the  inguinal  canal.  Remove  the  peritoneum 
from  Poupart's  Ligament  and  the  Iliac  Vessels.  Clean 
the  posterior  surface  of  Gimbernat's  Ligament  and 
define  the  Femoral  Ring.  Note  the  Transversahs 
Fascia  following  the  Iliac  Vessels  under  Poupart's 
Ligament.  Note  the  Iliac  Fascia  following  the  under 
surface  of  the  Iliac  Vessels  under  the  ligament  where  it 
joins  with  the  Transversalis  Fascia  to  form  the  sheath 
of  the  Femoral  Vessels.  Clean  the  Obturator  Artery. 
It  is  sometimes  a  branch  of  the  External  Iliac,  some- 
times a  branch  of  the  Deep  Epigastric. 

ABDOMINAL   CONTENTS 

After  the  abdominal  wall  has  been  thoroughly 
dissected,  its  upper  portion  should  be  divided  verti- 
cally, slightly  to  the  left  of  the  umbilicus.  The  flaps 
should  be  reflected  upwards  and  outwards.  Note  the 
Round   Ligament  of  the  Uver  running  upwards  and 


ABDOMINAL  CONTENTS  69 

outwards  from  the  umbilicus.  Study  the  disposition  of 
the  Great  (or  Gastrocohc)  Omentum.  Study  the  dis- 
position and  the  distinguishing  features  of  the  Small 
and  Large  Intestines.  Identify  the  subdivisions  of  each. 
Carefully  work  out  the  Superior  Mesenteric  Artery 
(a.  mesenterica  superior)  and  then  the  Inferior  Mesen- 
teric Artery  (a.  mesenterica  inferior).  Work  out  the 
blood-supply  of  the  Appendix  Vermiformis  (processus 
vermiformis) .  Tie  two  strong  ligatures  around  the 
Small  Intestine  just  below  the  Duodenum,  and  divide 
the  intestine  between  them.  In  the  same  way  tie  two 
ligatures  around  the  Large  Intestine  just  above  the 
Rectum,  and  divide  it.  Tie  the  Superior  Mesenteric 
Vessels  close  to  their  origin  and  cut  away  the  Mesen- 
tery. In  the  same  way  tie  the  Inferior  Mesenteric 
Vessels  and  remove  the  Mesocolon.  Free  the  Cecum 
and  Ascending  Colon  from  their  attachment  to  the 
abdominal  wall.  Remove  all  the  foregoing  structures 
from  the  abdomen,  but  no  other  abdominal  organ  is 
to  be  removed  at  any  time.  Remove  the  Lesser  (or 
Gastrohepatic)  Omentum.  In  front  of  the  commence- 
ment of  the  abdominal  aorta,  look  for  and  isolate  the 
Solar  Plexus  (plexus  coeliacus).  Immediately  to  the 
left  of  the  Cehac  Axis  (a.  coeliaca)  look  for  and  isolate 
the  Left  Semilunar  Ganglion  (g.  coeliacum),  with  the 
Left  Large  and  Small  Splanchnic  Nerves  entering  into 
its  lower  part  from  above.  To  the  right  of  the  Cehac 
Axis,  on  the  front  of  the  right  crus  of  the  diaphragm, 
look  for  and  clean  the  Diaphragmatic  Ganglion  (g. 
phrenicum).  Be  careful  not  to  injure  the  Inferior 
Phrenic  Artery  as  it  crosses  the  crus  directly  behind 
the  gangUon  or  slightly  above  it. 


70  DISSECTION  METHODS  AND  GUIDES 

Slightly  below  the  level  of  the  Diaphragmatic  Gang- 
lion {<g.  phrenicum)  look  for  the  Right  Great  Splanch- 
nic Nerve  as  it  passes  outwards  from  behind  the  right 
cms  of  the  diaphragm.  Follow  the  Great  Splanchnic 
Nerve  and  it  will  lead  you  to  the  Right  Semilunar 
Ganglion  (ganglion  cceliacum). 

Emerging  from  behind  the  right  crus  of  the  dia- 
phragm, in  the  same  way  as  did  the  Great  Splanchnic, 
but  at  a  lower  level,  you  will  find  the  Right  Lesser 
Splanchnic  Nerve,  which,  when  followed,  will  lead  to 
the  Right  Renal  Ganglion  on  the  Right  Renal  Artery. 

It  will  now  be  necessary  to  divide  the  communica- 
tions between  the  right  and  left  portions  of  the  Solar 
Plexus  {plexus  cceliacus)  in  order  to  fully  expose  the 
Celiac  Axis  (a.  coeliaca).  Let  its  Hepatic  and  Splenic 
Branches  alone  until  later,  but  follow  out  the  Gastric 
(Middle  Branch)  now.  Remove  the  entire  Great  Omen- 
tum (gastrocolic)  and  fully  expose  the  arterial  ''Gastro- 
epiploic Arch."  On  the  cardiac  end  of  the  stomach, 
look  for  the  Vasa  Brevia  (aa.  gastricce  breves)  Branches 
of  the  Splenic  Artery  (a.  lienatis) .  Free  the  Spleen  and 
the  ''Tail"  of  the  Pancreas  from  their  attachments  to 
the  abdominal  wall.  Lift  up  the  stomach,  spleen,  and 
pancreas,  and  turn  them  upwards,  all  at  the  same  time. 

Work  out  the  Splenic  Artery  (a.  lienalis)  and  its 
branches,  the  Vasa  Brevia  (aa.  gastricce  breves)  and 
Gastro-epiploica  Sinistra.  Just  below  the  origin  of  the 
Renal  Arteries,  look  for  the  Spermatic  (or  Ovarian) 
Arteries,  and  isolate  them  now  before  they  get  injured. 

Return  to  the  celiac  axis  and  clean  the  Pancreatico- 
duodenal Branch  of  the  Hepatic  Artery.  Free  the 
"Head"  of  the  Pancreas  and  the  descending  portion 


ABDOMINAL  CONTENTS  71 

of  the  Duodenum  from  their  attachments  to  the  ab- 
dominal wall.  Turn  the  Pancreas  and  Duodenum  up- 
wards and  clean  the  Common  Bile  Duct  {ductus  chole- 
dochus)  and  its  branches.  It  is  now  possible  to  clean 
the  main  trunk  of  the  Hepatic  Artery,  after  which  it 
becomes  easy  to  follow  out  and  clean  the  Portal  Vein. 

Clean  the  Renal  Veins  and  the  Left  Spermatic  (or 
Ovarian)  Vein.  Clean  the  upper  portion  of  the  Vena 
Cava  as  far  as  the  posterior  fissure  of  the  Hver,  then 
clean  the  Right  Spermatic  (or  Ovarian)  Vein.  Remove 
the  overlying  peritoneum  from  the  Kidneys  and 
Adrenals.  Remove  all  fat  from  around  them.  Free 
the  Kidneys  and  reflect  them  toward  the  midline. 

Clean  first  the  Renal  Arteries,  then  clean  the  Ureters, 
and  follow  the  latter  down  to  the  bladder. 

Strip  off  the  peritoneum  and  clean  the  Abdominal 
Aorta  and  both  Common  Iliac  Arteries.  Clean  the 
lower  portion  of  the  Vena  Cava  and  the  Common 
Iliac  Veins.  By  lifting  these  blood-vessels  forwards 
and  toward  the  left,  it  will  be  possible  to  expose  the 
Receptaculum  Chyli  (cisterna  chyli).  You  will  find  it 
lying  on  the  front  of  the  body  of  the  second  lumbar 
vertebra  in  the  interval  between  the  Aorta  and  the 
fleshy  portion  of  the  right  Crus  of  the  diaphragm. 
The  Vena  Azygos  Major  is  to  the  right  of  it. 

Clean  the  Receptaculum  ChyU  {cisterna  chyli), 
following  it  upwards  along  the  right  side  of  the  Aorta 
to  the  aortic  opening  of  the  diaphragm. 

Carefully  clean  the  upper  portion  of  the  Aorta  and 
then  clean  the  Esophagus. 

Clean  the  Phrenic  Arteries.  You  will  find  them 
coming  off  the  aorta  just  above  the  celiac  axis,  singly 


72  DISSECTION  METHODS  AND  GUIDES 

or  by  a  common  trunk,  then  running  outwards  across 
the  crura  of  the  diaphragm  under  cover  of  the  peri- 
toneum. 

Follow  the  thoracic  portions  of  the  Phrenic  Nerves 
through  to  the  under  surface  of  the  diaphragm  and 
trace  out  their  distribution. 

Locate  the  tip  of  the  left  transverse  process  of  the 
second  lumbar  vertebra.  Running  from  this  to  the 
tip  of  the  twelfth  rib  you  will  find  the  External  Arcuate 
Ligament  (arcus  lumbocostalis  lateralis),  arching  across 
the  front  of  the  Quadratus  Lumborum  Muscle. 

From  the  same  starting-point  you  will  find  the 
Internal  Arcuate  Ligament  (arcus  lumbocostalis  medi- 
alis)  arching  across  the  front  of  the  Psoas  Muscle  to 
reach  the  body  of  the  second  lumbar  vertebra. 

Clean  the  Crura  and  the  Intercrural  Arch  of  the 
Diaphragm. 

Remove  the  overlying  peritoneum  and  work  out 
the  Lumbar  and  Sacral  Plexuses.  In  cleaning  the 
sacral  plexus  be  careful  not  to  injure  the  Internal 
Pudic  (a.  pudenda  interna)  and  Sciatic  (a.  glutcea  infe- 
rior) Arteries. 

PELVIC   CONTENTS  IN  GENERAL 

Remove  the  parietal  peritoneum  and  clean  the 
Urachus  down  to  the  bladder.  Be  careful  in  doing 
so,  not  to  injure  the  Ureters,  Vasa  Deferentia  (or 
Round  Ligaments  of  the  Uterus),  or  the  Spermatic 
(or  Ovarian)  Arteries. 

The  Right  Vas  Deferens  (or  Round  Ligament)  and 
the  right  Spermatic  Artery  will  have  to  be  divided 
near  the  the  internal  abdominal  ring,  but  all  of  the 


PELVIC  CONTENTS  IN  GENERAL  73 

other  named  structures  must  be  freed,  so  that  they 
can  be  retracted  toward  the  midUne. 

Dismemberment  of  Lower  Extremity. — Remove  as 
much  as  you  can  of  the  peritoneum  covering  the 
pelvic  viscera.  Clean  tlie  Internal  Iliac  Arteries 
and  then  the  corresponding  veins.  The  Right  In- 
nominate Bone  (os  coxce)  is  to  be  disarticulated,  but 
before  doing  so,  carry  out  the  following  steps:  Divide 
the  right  external  iliac  vessels  between  two  ligatures. 
Divide  the  muscular  attachments  along  the  upper 
border  of  the  crest  of  the  right  ihum.  Divide  the 
Levator  Ani  Muscle  along  the  ''White  Line"  of  the 
obturator  fascia.  The  bladder  must  be  pushed  back 
out  of  the  way  and  the  Symphysis  Pubis  divided. 
Divide  the  muscles  and  fasciae  attached  along  the 
inner  side  of  the  lower  border  of  the  Ischiopubic  Ramus. 
Divide  the  Lumbar  and  Sacral  Plexuses  and  the  Psoas 
Muscle.  Disarticulate  the  Sacro-iliac  Joint.  This  can 
readily  be  done  from  in  front  if,  while  doing  so,  the 
divided  symphysis  be  forced  widely  apart.  Sever  the 
remaining  Sacro-iliac  Ligaments,  the  Greater  and  Lesser 
Sacrosciatic  Ligaments,  and  the  Pyraformis  Muscle. 
After  the  removal  of  the  right  extremity,  trim  away 
the  ragged  edges  of  the  Perineal  Muscles. 

Trace  the  Obliterated  Left  Hypogastric  Artery 
down  to  the  Anterior  Division  of  the  Internal  Iliac 
Artery.  Using  your  finger,  carefully  free  the  ante- 
rior wall  of  the  bladder.  This  opens  up  the  ''Cave  of 
Retzius."  In  the  same  way  carefully  free  the  Rectum 
on  all  sides.  Use  only  your  finger,  in  order  to  be  sure 
not  to  destroy  any  of  the  arteries.  Clean  the  Middle 
Sacral  Artery  and  then  the  two  Lateral  Sacral  Branches 


74  DISSECTION  METHODS  AND  GUIDES 

of  the  Posterior  Division  of  the  Internal  Ihac  Artery. 
Isolate  the  Superior  Hemorrhoidal  Branch  of  the  In- 
ferior Mesenteric  Artery,  and  then  the  Middle  Hemor- 
rhoidal Branch  of  the  Anterior  Division  of  the  Internal 
Iliac  Artery.  Thoroughly  clean  the  surface  of  the 
Rectum,  trace  out  the  Inferior  Hemorrhoidal  Branch 
of  the  Internal  Pudic  (a.  pudenda  interna),  clean  the 
Internal  Sphincter  Ani  Muscle  and  the  back  part  of 
the  Levator  Ani  Muscle.  It  may  be  found  necessary 
to  temporarily  remove  the  packing  from  the  rectum, 
but  it  should  later  be  repacked,  less  tightly  than  at 
first. 

PELVIC  VISCERA   (MALE) 

Carefully  trace  the  Ureters  and  the  Vasa  Deferen- 
tia  {ductus  deferentes)  to  the  back  of  the  base  of  the 
bladder.  At  the  point  where  the  Obliterated  Hypo- 
gastric Artery  joins  the  Anterior  Division  of  the 
Internal  Iliac  you  will  find  the  Superior  Vesical 
Artery.  Trace  out  this  artery  over  the  fundus  of  the 
bladder.  Look  for  and  clean  the  Middle  Vesical 
Artery.  This  artery  may  be  a  branch  of  the  Superior 
Vesical  or,  as  is  often  the  case,  both  arteries  may  be 
branches  of  the  Hypogastric,  which  has  remained 
patent  at  its  lower  end.  Coming  off  the  anterior 
division  of  the  Internal  Iliac  close  to  or  in  common 
with  the  Middle  Hemorrhoidal,  look  for  the  Inferior 
Vesical  Artery,  and  carefully  trace  out  its  branches. 

The  fundus  of  the  bladder  may  later  be  opened 
transversely.  Further  instructions  are  given  fol- 
lowing those  for  the  female  pelvis. 

Carefully  isolate  the  Vesiculse  Seminales,  then  clean 
the  Prostate  and  Membranous  Urethra. 


PELVIC  CONTENTS  IN  GENERAL  75 

PELVIC  VISCERA   (FEMALE) 

Using  your  finger  only,  free  the  anterior  wall  of  the 
bladder.  Separate  the  bladder  from  the  uterus  and 
vagina,  then  separate  the  rectum  from  the  uterus  and 
vagina. 

The  dissection  of  the  rectum  and  its  arteries  has 
already  been  given  (q.  v.). 

Isolate  the  Ovarian  Arteries.  Trace  out  the  Round 
Ligament  of  the  Uterus.  Note  the  Small  Funicular 
Artery  which  is  accompanying  it.  Trace  the  Uterine 
Artery.  You  will  find  it  coming  off  the  anterior 
division  of  the  Internal  Iliac  close  to,  or  in  common 
with,  the  Middle  Hemorrhoidal  or  the  Inferior  Vesical. 
Isolate  the  Ureters  down  to  the  bladder.  Trace  out  the 
Vaginal  Branches  of  the  Anterior  Division  of  the 
Internal  Iliac.  Remove  the  packing  from  the  vagina. 
Clean  the  surface  of  the  vagina  on  all  sides,  and  on 
its  front  surface  trace  out  the  Azygos  Vaginae  Artery. 
Clean  the  Sphincter  Vaginae  Muscle.  The  vagina  may 
later  be  opened  laterally.  The  dissection  of  the  blad- 
der and  its  blood-supply  has  already  been  given  {q.  v.). 

PELVIC   CONTENTS  IN  GENERAL   (Concluded) 

Retract  the  Pelvic  Viscera  towards  the  right  side. 
Clean  the  pelvic  portions  of  the  Internal  Pudic,  Obtu- 
rator, and  Sciatic  Arteries. 

Reflect  the  Psoas  Muscle  toward  the  midline,  and 
trace  out  the  pelvic  portions  of  the  Gluteal  and  Ilio- 
luinbar  Branches  of  the  Posterior  Division  of  the 
Internal  Iliac  Artery. 

Remove  all  loose  fat  and  clean  the  anterior  portion 
of  the  Levator  Ani  Muscle. 


76  DISSECTION  METHODS  AND  GUIDES 

Clearly  define  the  "White  Line"  of  the  Obturator 
Fascia. 

SPERMATIC   CORD  AND   TESTICLE.     (See  Fig.  11.) 

Make  an  incision  from  the  external  abdominal  ring 
down  the  side  of  the  Scrotum.  The  scrotum  consists 
of  an  outer  layer  (skin)  and  an  inner  layer  (Dartos), 
which  also  forms  its  septum.  The  skin  and  dartos 
are  not  readily  separable,  and  it  need  not  be  attempted. 
It  is  easy,  however,  to  shell  out  the  testicle  and  cord 
with  their  outer  coverings,  because  the  only  point 
of  adhesion  between  the  Dartos  and  the  External 
Spermatic  Fascia  is  just  opposite  the  lower  end  of  the 
testicle,  and  it  is  not  extensive  nor  is  it  hard  to  tear 
away.  Free  the  testicle  and  cord  with  your  finger 
and  lift  them  out  of  the  scrotum.  Open  the  Tunica 
Vaginalis  and  expose    the    Testicle  and  Epididymis. 

On  the  front  end  of  the  testicle  note  the  Hydatid  of 
Morgagni.  On  the  outer  side,  between  the  border  of 
the  testicle  and  the  epididymis,  note  the  Digital 
Fossa.  Incise  the  visceral  layer  of  the  Tunica  Vaginalis 
along  the  outer  side  of  the  epididymis.  Carefully 
separate  the  Vas  Deferens  {ductus  deferens)  from  the 
back  of  the  epididymis.  Between  them,  at  the  lower 
part,  look  for  the  Vas  Aberrans,  much  doubled  up  on 
itself  and  3  to  15  inches  long.  Incise  longitudinally 
the  Intercolumnar  (External  Spermatic)  Fascia  at 
the  upper  part  of  the  cord.  This  will  expose  the 
muscular  loops  of  the  Cremasteric  (Middle  Spermatic) 
Fascia  and  the  Cremasteric  Artery.  Separate  the 
loops  of  the  Cremasteric  Fascia  and  expose  the  In- 
fundibuliform    (Internal    Spermatic)    Fascia.      Upon 


PENIS  AND  MALE  URETHRA  77 

opening  the  infundibuliform  fascia,  you  will  encounter 
an  unnamed  laminated  prolongation  of  the  sub- 
peritoneal tissue,  surrounding  the  cord  and  binding 
its  elements  together.  This  layer  corresponds  to  the 
visceral  layer  of  the  tunica  vaginaHs  of  the  testicle, 
while  the  infundibuliform  fascia  corresponds  to  the 
parietal  layer  of  the  tunica  vaginalis.  Incise  this 
visceral  layer  of  the  Infundibuliform  Fascia  and  sepa- 
rate the  structures  forming  the  cord. 

The  front  part  of  the  cord  consists  mainly  of  the 
large  mass  of  the  Pampiniform  Plexus  of  Veins  sur- 
rounding the  large  Spermatic  Artery.  The  back  part 
of  the  cord  consists  of  the  hard,  cord-like  Vas  Deferens 
(ductus  deferens),  accompanied  by  a  smaller  Deferen- 
tial Artery  and  the  smaller  mass  of  Deferential  Veins. 
At  the  inguinal  portion  of  the  cord,  look  for  the  funicu- 
lar Processus  Vaginalis  of  the  Peritoneum  (Ligament 
of  Cloquet).  In  the  inguinal  canal  it  is  usually  above 
the  other  elements  of  the  cord;  then  it  runs  down 
their  outer  side  to  the  tunica  vaginalis.  When  obliter- 
ated it  is  usually  a  thin  thread-like  cord,  but  sometimes 
it  is  patent,  and  may  then  become  enlarged  into  a 
' 'hydrocele  of  the  cord." 

PENIS  AND   MALE  URETHRA 

Incise  the  skin  along  the  midline  of  the  dorsum  of 
the  penis  from  the  mons  veneris  to  the  corona,  then 
laterally  around  the  neck,  just  back  of  the  glans,  to  the 
frenum.  Reflect  this  skin-dartos  layer  laterally.  Trace 
out  the  Superficial  Dorsal  Vein  lying  in  the  areolar 
layer. 

Clean  the  Suspensory  Ligament.     Incise  the  Deep 


78  DISSECTION  METHODS  AND  GUIDES 

Fascia  in  the  same  way  that  you  did  the  skin-dartos 
layer  and  reflect  in  the  same  way.  In  the  dorsal  mid- 
line look  for  the  Deep  Dorsal  Vein,  and  on  each  side 
of  the  vein  look  for  a  Dorsal  Artery,  and  on  the  outer 
side  of  each  artery  look  for  a  Dorsal  Nerve. 

In  the  Sulcus,  below  and  between  the  Corpora 
Cavernosa,  isolate  the  Corpus  Spongiosum  (corpus 
cavernosum  urethrce). 

Incise  the  Tunica  Albuginia  laterally,  and  ex- 
amine the  structure  of  one  of  the  Corpora  Cavernosa. 
Incise  the  Tunica  Albuginia  and  both  Corpora  Caver- 
nosa transversely.  Note  the  tunica  albuginia  enter- 
ing between  the  corpora,  forming  the  Septum  Pectini- 
forme.  Lay  open  the  Urethra  along  its  under  side 
from  the  meatus  to  the  membranous  portion. 

The  membranous  and  prostatic  urethra  and  the 
bladder  are  best  seen  when  layed  open,  respectively, 
from  above  and  in  front.  In  order  to  do  this,  it  is  now 
permissible  to  remove  them  from  the  pelvis. 

THE   MUSCLES   OF  THE  BACK 

The  Trapezius,  both  Rhomboidei,  and  the  Latis- 
simus  Dorsi  have  already  been  dissected,  and  should 
all  be  detached  from  the  spine  and  removed.  Clean 
the  Serratus  Posticus  Superior,  detach  it  from  the 
spine,  and  reflect  it  outwards.  Clean  the  Serratus 
Posticus  Inferior,  but  do  not  divide  it  in  any  way. 
Thoroughly  clean  the  Vertebral  Aponeurosis,  incise 
it  throughout  its  length,  close  to  the  spine,  and  re- 
flect it  outwards,  away  from  the  spine.  Separate 
the  Erector  Spinse  Mass  into  its  outer,  middle,  and 
inner  columns. 


SPINAL  CORD  79 

SPINAL  CORD 

The  usual  procedure  is  to  open  the  Neural  Canal, 
throughout  its  length,  from  behind. 

Another  method,  which  sometimes  proves  useful, 
is  to  open  the  cervical,  thoracic,  and  lumbar  portions 
of  the  Neural  Oanal  from  in  front,  the  sacral  portion 
being  opened  from  behind. 

In  the  first  method,  which  is  the  more  convenient, 
it  is  necessary  to  first  remove  the  muscles  which 
occupy  the  spinal  groove,  on  each  side  of  the  spinous 
processes,  before  removing  the  neural  arches  of  all  of 
the  vertebrae  and  the  sacrum.  In  removing  the  neural 
arches  it  is  best  to  begin  with  the  upper  thoracic 
vertebrae  by  sawing  through  the  laminae  on  each 
side,  and  continuing  in  this  way  down  to  the  sacrum. 
In  the  cervical  region  and  the  sacrum  it  is  more  con- 
venient to  divide  the  laminae  with  bone-forceps.  The 
secret  of  using  bone-forceps  with  ease  and  rapidity,  is 
to  avoid  trying  to  cut  away  too  much  at  a  time.  Small 
bites  are  not  only  easier  to  cut,  but  also  lead  to  accuracy 
and  rapidity,  without  danger  of  breaking  the  forceps. 

In  opening  the  neural  canal  from  in  front,  your 
object  is  to  remove  the  bodies  of  the  vertebrae  instead 
of  their  neural  arches. 

In  the  cervical  region,  use  bone-forceps  for  cutting 
the  costotransverse  processes. 

In  the  thoracic  region,  divide  the  necks  of  the  ribs 
with  bone-forceps  and  remove  the  heads  of  the  ribs, 
then  cut  through  the  pedicles  of  the  vertebrae  with 
a  sharp  flat  chisel  or  an  osteotome.  In  the  lower 
thoracic  and  lumbar  vertebrae  you  can  saw  through 
the  pedicles. 


80  DISSECTION  METHODS  AND  GUIDES 

It  is  always  more  convenient  to  open  the  sacral 
portion  of  the  neural  canal  with  bone-forceps  from 
behind. 

Opening  the  neural  canal  from  in  front  has  the  ad- 
vantage of  making  it  easy  to  get  out  all  of  the  spinal 
nerves,  but  it  has  the  great  disadvantage  of  utterly 
ruining  a  good  dissection  of  the  thorax  and  abdomen. 

When  the  neural  canal  has  been  opened  for  its 
entire  length,  divide  the  membranes  as  close  to  the 
foramen  magnum  as  you  can. 

Withdraw  the  Spinal  Nerves  as  far  as  you  can  by 
gentle  traction,  and  divide  them  as  close  to  the  inter- 
vertebral foramina  as  may  be  possible.  Try  to  divide 
the  Spinal  Nerves  beyond  their  ganglia.  If  the  specimen 
is  quite  fresh,  it  will  be  better  to  harden  it  by  placing 
it  in  alcohol  or  formalin  for  a  few  days  before  dissect- 
ing it.  The  specimen  should  then  be  pinned  down  in 
a  black,  wax-lined  tray  and  dissected  under  water.  If 
the  specimen  is  not  fresh,  there  will  be  no  advantage 
in  attempting  to  harden  it. 

Pin  the  specimen  down  with  its  posterior  surface 
uppermost.  Open  the  Dura  longitudinally  in  the 
midline,  reflect  it  laterally,  split  it  outwards  over 
several  of  the  spinal  nerves,  then  pin  it  down.  This 
exposes  the  Arachnoid. 

Along  the  sides  midway  between  the  spinal  nerves 
note  the  processes  of  the  Ligamentum  Denticulatum 
(Dentate  Ligament).  Note  also  that  there  are  none 
below  the  point  where  the  cord  terminates.  It  is  a 
good  plan  to  partly  fill  the  subarachnoid  space  with  air. 
A  blowpipe  will  serve  for  that  purpose.  By  pressing 
the  air  from  place  to  place,  it  becomes  easy  to  define 


SPINAL  CORD  81 

the  extensions  and  limits  of  the  subarachnoid  space. 
For  example,  it  will  enable  you  to  see  that  the  processes 
of  the  dentate  ligament  are  merely  covered  by  the 
arachnoid.    Open  the  Arachnoid  by  a  mesial  incision. 

On  each  side,  just  back  of  the  posterior  roots  of  the 
spinal  nerves,  look  for  the  Posterior  Spinal  Arteries. 
Reverse  the  specimen  and  pin  it  down  with  its  anterior 
surface  uppermost.  Open  the  Dura  and  Arachnoid 
in  the  same  way  as  before.  Note  the  processes  of  the 
dentate  ligament,  and  the  smaller,  more  widely  spread 
anterior  roots  of  the  spinal  nerves. 

In  the  middle  of  the  front  surface  of  the  cord  note 
the  Linea  Splendens;  trace  it  downwards  and  isolate 
the  Filum  Terminale  from  among  the  nerve-roots 
constituting  the  Cauda  Equina.  Incise  the  Pia  Mater 
close  to  the  linea  splendens  and  look  for  the  Anterior 
Spinal  Artery.  Split  the  investment  of  a  spinal  nerve 
and  its  ganglion. 

It  may  be  possible  to  make  transverse  sections  of  the 
cord  itself  at  various  levels. 


UPPER  EXTREMITY 

Order  of  Dissections 

1.  Trapezius  and  Latissimus  Dorsi. 

2.  Shoulder. 

3.  Pectoral  Muscles  and  Axilla. 

4.  Arm. 

5.  Dismemberment. 

6.  Forearm,  superficial  dissection. 

7.  Back  of  Forearm  and  Hand. 

8.  Palm  of  Hand,  superficial  dissection. 

9.  Front  of  Forearm,  deep  dissection. 

10.  Antecubital  Space. 

11.  Hand,  deep  dissection. 

TRAPEZroS  AND  LATISSIMUS  DORSI 

Make  a  skin  incision  in  the  midline  of  the  back,  ex- 
tending from  the  root  of  the  neck  to  the  level  of  the 
sacrum. 

From  the  lower  end  of  this  incision,  make  another, 
following  the  crest  of  the  ilium  outwards,  as  far  as 
the  middle  of  the  crest.  From  near  the  outer  end 
of  the  acromion  process,  make  an  incision  following 
the  line  of  the  spine  of  the  scapula  to  the  midline 
incision.  Beginning  in  the  midUne  incision,  reflect  the 
skin  outwards  as  far  as  the  posterior  axillary  line.  Clean 
the  thoracic  portion  of  the  Trapezius  Muscle,  working 
from  the  midline  outwards.  Carefully  free  its  outer 
border,  and  free  the  entire  muscle  from  the  underlying 
muscles. 

82 


TRAPEZIUS  AND  LATISSIMUS  DORSI  83 


Fig.  5. — Back  of  Arm  and  Back  op  Thorax. 

Knife  incisions  are  indicated  by  continuous  red  lines.     Where  the  skm  should 

be  cut  with  scissors  is  shown  by  dotted  red  hnes. 


84  DISSECTION  METHODS  AND  GUIDES 

Clean  all  of  the  Latissimus  Dorsi  Muscle,  working 
upwards  and  outwards  from  the  midline.  Define  its 
outer  border  and  thoroughly  free  this  muscle  from  the 
underlying  muscles.  Divide  the  Right  Trapezius 
along  its  spinal  attachment.  In  order  to  avoid  cutting 
the  Rhomboidei  at  the  same  time,  it  is  best  to  use 
blunt-pointed  scissors  and  to  carefully  free  the  muscle 
in  advance  with  your  fingers,  and  to  cut  it  about  1  inch 
from  the  spine.  The  thoracic  portion  of  the  Right 
Trapezius  should  be  reflected  upwards,  and  left  at- 
tached to  the  spine  of  the  scapula. 

Divide  the  Left  Trapezius  along  its  attachment 
to  the  spine  of  the  scapula;  carefully  free  it  from  the 
underlying  muscles  and  reflect  it  toward  the  midhne. 
The  dissection  of  the  cervical  portion  of  the  Trap- 
ezius is  described  with  the  Superficial  Dissection  of 
the  Back  of  the  Neck  {q.  v.). 

SHOULDER 

After  the  upper  portion  of  the  Trapezius  has  been 
dissected,  clean  the  lower  part  of  the  Levator  Anguli 
Scapulae  (m.  levator  scapulce).  Under  this  muscle,  look 
for  and  clean  the  Posterior  Scapular  Branch  (ramus 
descendens)  of  the  Transverse  Cervical  Artery  (a.  trans- 
versa colli)  from  the  Thyroid  Axis  (truncus  thyreocervi- 
calis).    Clean  the  Supraspinatus  Muscle. 

At  the  upper  border  of  the  scapula,  near  the  base  of 
the  coracoid  process,  look  for  the  Suprascapular 
(a.  transversa  scapulce)  Branch  of  the  Thyroid  Axis 
(truncus  thyreocervicalis) .  Passing  through  the  supra- 
scapular notch  just  beneath  the  Suprascapular  Artery 
(a.    transversa   scapulce),   look   for   the   Suprascapular 


SHOULDER  85 

Nerve  (n.  suprascapularis) .  Be  careful  not  to  injure 
the  Omohyoid  Muscle  (m.  omohyoideus) . 

Clean  the  Infraspinatus  Muscle  and  the  Teres 
Minor  Muscle,  but  do  not  attempt  to  separate  them 
until  after  you  have  identified  their  insertions  on  the 
humerus.  By  following  back  their  tendons  it  becomes 
quite  easy  to  separate  them.  However,  it  will  be  best 
not  to  attempt  this  until  the  Deltoid  Muscle  has  been 
cleaned  and  can  be  Hfted  up  without  being  cut.  Clean 
the  Teres  Major  Muscle,  and  separate  it  above,  from 
the  Teres  Minor  and  below,  from  the  Latissimus 
Dorsi.  Clean  the  Rhomboideus  Minor  and  the  Rhom- 
boideus  Major  Muscles. 

With  the  arm  at  the  side  of  the  body,  make  an 
incision  from  the  outer  end  of  the  acromion  process 
down  the  outer  side  of  the  arm  to  a  point  at  least 
2  inches  below  the  outer  condyle  of  the  humerus. 
Reflect  the  skin  far  enough  on  each  side  of  this  incision 
to  fully  expose  the  deltoid.  Do  not  make  any  knife 
incision  along  the  clavicle;  it  is  much  safer  to  snip 
the  skin  with  scissors  as  you  advance.  Thoroughly 
clean  the  Deltoid  Muscle,  working  from  above  down- 
wards. Be  careful  not  to  injure  the  Cephalic  Vein  or 
the  Humeral  Branch  (ramus  deltoideus)  of  the  Acromio- 
thoracic  Artery  (a.  thoracoacromialis)  (or  Thoracic 
Axis),  both  of  which  you  will  find  in  the  interval  be- 
tween the  anterior  border  of  the  Deltoid  and  the 
Pectoralis  Major.  The  Deltoid  must  not  be  divided. 
By  abducting  the  arm  it  is  possible  to  relax  the  Deltoid 
sufficiently  to  allow  of  your  thoroughly  freeing  it  and 
lifting  it  up  far  enough  to  clean  and  separate  the  under- 
lying tendons.    Clean  the  tendons  of  the  Infraspinatus 


86  DISSECTION  METHODS  AND  GUIDES 

and  Teres  Minor,  separate  the  muscles,  and  look  for 
the  Dorsalis  Scapulae  (a.  circumfiexa  scapulce)  Branch 
of  the  Subscapular  Artery.  You  will  find  it  running 
upwards  under  cover  of  the  Infraspinatus  Muscle. 

Clean  the  tendinous  upper  portions  of  the  outer 
head  and  the  long  head  of  the  Triceps  (triceps  brachii). 
Between  them,  emerging  from  the  Quadrilateral  Space, 
look  for  the  Circumflex  Nerve  (n.  axillaris)  and  the 
Posterior  Circumflex  (a.  circumfiexa  humeri  posterior) 
Branch  of  the  Axillary  Artery  (a.  axillaris).  In  the 
interval  between  the  Teres  Minor  and  the  Teres  Major, 
look  for  the  lower  branch  of  the  Dorsahs  Scapulae 
Artery  (a.  circumfiexa  scapulce). 

THE  PECTORAL  MUSCLES  AND  AXILLA 

Make  a  midline  incision  from  the  suprasternal  notch 
to  the  Ensif orm  Process  (or  Xiphoid  Appendix) .  Begin 
in  this  incision  and  reflect  the  skin  outwards,  dividing 
it  along  the  line  of  the  clavicle  with  scissors.  Do  not 
make  any  knife  incision  along  the  clavicle.  Remove 
the  skin  from  the  arm  as  far  down  as  the  bend  of  the 
elbow.  At  the  level  of  the  bend  of  the  elbow,  the  skin 
must  be  cut  circularly  around  with  scissors,  not  a 
knife.  Always  avoid  transverse  knife  incisions  of  the 
skin  whenever  it  is  possible  to  do  so. 

Clean  the  Pectoralis  Major  Muscle  and  remove  all 
of  its  sheath  clear  to  the  axillary  border,  working  from 
the  midline  outwards,  with  a  pair  of  blunt-pointed 
scissors  ' 'curved  on  the  flat."  Free  the  axillary  border 
of  the  Pectoralis  Major  with  your  fingers.  Do  not 
use  a  knife  in  the  axilla  for  any  purpose  whatever. 
In  the  axilla,  use  only  your  forceps  or  your  fingers, 


THE  PECTORAL  MUSCLES  AND  AXILLA 


87 


Fig.  6. — Pectoral  Region  and  Front  of  Arm  and  Forearm. 

Ejiife  incisions  are  indicated  by  continuous  red  lines.      The  dotted  red  lines 

show  where  the  skin  should  be  cut  with  scissors. 


88  DISSECTION  METHODS  AND  GUIDES 

and  blunt-pointed  scissors,  sometimes;  but  a  knife, 
never.  In  the  loose  cellular  tissue  of  the  axilla,  look 
for  the  Intercostohumeral  Nerve  (n.  intercostohrachi- 
alis);  there  may  be  two.  You  will  find  it  running 
parallel  to,  but  just  hidden  by,  the  axillary  border  of 
the  PectoraUs  Major  Muscle.  In  order  not  to  injure 
the  nerve,  tear  the  loose  cellular  tissue  transversely 
with  two  pairs  of  forceps  or  with  your  fingers. 

Follow  the  Intercostohumeral  Nerve  (n.  intercosto- 
hrachialis)  down  the  arm  and  clean  it  carefully. 

Clean  the  axillary  border  of  the  Latissimus  Dorsi 
Muscle.  In  the  loose  cellular  tissue  just  in  front  of  it, 
look  for  the  Posterior  Thoracic  Nerve — External 
Respiratory  of  Sir  Charles  Bell — (n.  thoracalis  longus)^ 
running  downwards  on  the  chest  wall.  Thrust  your 
fingers  under  the  Pectoralis  Major,  lift  it  up  gently, 
and  feel  for  the  vessels  and  nerves  which  enter  it  from 
behind.  Having  definitely  located  them,  divide  the 
muscle  with  a  pair  of  scissors  just  externally  to  its 
nerve  and  blood-supply.  Divide  its  clavicular  origin 
close  to  the  bone,  and  reflect  it  outwards.  Remove  all 
the  underlying  areolar  tissue,  fat,  and  lymphatics,  and 
clean  the  Pectorahs  Minor  Muscle  and  the  Costocora- 
coid  Membrane  {fascia  coracoclavicularis) .  Free  the 
outer  border  of  the  Pectoralis  Minor.  Locate  the 
blood-vessels  and  nerves  which  enter  it  from  behind. 
Divide  it  just  above  them  and  reflect  it  and  the  Costo- 
coracoid  Membrane  {fascia  coracoclavicularis)  upwards 
and  inwards. 

Do  not  attempt  to  remove  any  of  the  fat  or  lymphatic 
glands  from  the  axilla  itself,  until  all  of  the  important 
structures  in  it  have  first  been  thoroughly  isolated. 


THE  ARM  89 

Incise  the  Superficial  Fascia  over  the  BasiUc  Vein 
(v.  basilica)  in  the  arm.  Pick  up  the  BasiHc  Vein  (v. 
basilica),  clean  it  carefully,  and  follow  it  up  into  the 
axilla  and  clean  the  Axillary  Vein  {v.  axillaris).  It 
will  be  necessary  to  tie  and  cut  ofif  many  of  the  small 
branches  (tributaries)  of  both  these  veins.  Clean  the 
upper  part  of  the  Brachial  Artery,  follow  it  up  into  the 
axilla,  and  clean  the  Axillary  Artery.  You  must  not 
divide  an}''  one  of  the  branches  of  these  arteries,  but 
should  you  do  so  accidentally,  immediately  tie  it  to- 
gether again  with  a  piece  of  fine  thread.  In  cleaning 
these  arteries,  remove  their  sheath  and  their  venae 
comites  as  well.  Carefully  clean  each  of  the  branches 
of  the  Axillary  Artery.  The  branch  requiring  the 
most  care  is  the  small  Anterior  Circumflex  Artery 
(a.  circumfiexa  humeri  anterior).  It  runs  between  the 
Coracobrachialis  Muscle  and  the  tendon  of  the  Latis- 
simus  Dorsi.  Isolate  and  clean  the  large  Nerve-bundle 
of  the  Brachial  Plexus. 

Clean  the  tendons  of  the  Pectoralis  Major,  Latis- 
simus  Dorsi,  and  Subscapularis.  Remove  all  of  the 
fat  and  lymphatic  glands  from  the  Axilla  and  from 
behind  the  Costocoracoid  Membrane.  Clean  the  Sub- 
clavius  Muscle.  Finish  cleaning  the  Subscapular  Ar- 
tery. Clean  the  Subscapularis  Muscle  and  the  Serratus 
Magnus  (m.  serratus  anterior)  Muscle.  Separate  and 
clean  the  Cords  of  the  Brachial  Plexus. 

THE  ARM 

Clean  the  CephaUc  Vein;  then  remove  all  the  fat 
and  the  superficial  fascia  as  far  down  as  the  bend  of  the 
elbow.    Be  careful  not  to  divide  the  Intercostohum- 


90  DISSECTION  METHODS  AND  GUIDES 

eral  Nerve  (n.  intercostobrachialis) .  Clean  the  Biceps 
Muscle.  Finish  cleaning  the  Basilic  Vein.  It  may  be 
necessary  to  tie  and  cut  away  many  of  its  smaller 
tributaries.  Clean  the  Median  Nerve  {n.  medianus), 
and  then  clean  the  Brachial  Artery,  but  do  not  yet 
attempt  to  follow  out  its  branches. 

Clean  the  Musculocutaneous  Nerve  and  the  Coraco- 
brachialis  Muscle.  Clean  the  posterior  surface  of  the 
Biceps  and  the  anterior  surface  of  the  Brachialis 
Anticus  Muscle  (m.  brachialis).  Clean  the  Ulnar 
Nerve  (n.  ulnaris)  and  both  of  the  Internal  Cutaneous 
Nerves  {nn.  cutanei,  antehrachii  et  hrachii  mediales). 
Clean  the  Circumflex  Nerve  (n.  axillaris),  Musculo- 
spinal Nerve  (n.  radialis),  and  the  Superior  Profunda 
(a.  profunda  hrachii)  Branch  of  the  Brachial  Artery. 
Clean  the  Triceps  Muscle. 

Clean  the  remaining  branches  of  the  Brachial  Artery, 
but  do  not  attempt  to  follow  any  of  them  below  the 
level  of  the  elbow. 

DISMEMBERMENT 

As  soon  as  progress  in  the  dissection  of  the  shoulder, 
neck,  and  thorax  will  admit  of  it,  the  arm  should  be 
dismembered  from  the  body.  If  several  students  are 
working  at  the  same  time  on  the  same  side  of  the 
body,  this  will  save  time  and  avoid  much  confusion 
and  inconvenience.  The  procedure  is  as  follows:  Saw 
through  the  middle  of  the  Clavicle,  divide  the  Sub- 
clavius  Muscle,  and  the  Clavicular  Attachment  of  the 
Trapezius.  Tie  two  ligatures  on  the  Axillary  Vein 
and  divide  it  between  the  ligatures.  Do  the  same  with 
the  first  part  of  the  Axillary  Artery. 


FOREARM,  SUPERFICIAL  DISSECTION  91 

Assemble  the  cords  of  the  Brachial  Plexus,  surround 
them  with  a  strong  ligature  and  divide  them  above  it 
Divide  the  scapular  attachments  of  the  Omohyoid, 
upper  portion  of  the  Trapezius,  and  the  Levator 
AnguU  Scapulae.  Divide  the  Latissimus  Dorsi  just 
below  its  tendon,  and  both  of  the  Rhomboidei,  close  to 
their  spinal  attachment.  Study  the  Serratus  Magnus 
(m.  serratus  anterior)  carefully  before  dividing  it 
about  2  inches  from  the  spinal  border  of  the  scapula. 
Remove  the  ligature  from  the  Axillary  Vein,  compress 
and  rub  upwards  all  the  veins  of  the  forearm  and  arm 
in  order  to  completely  express  their  contents.  This 
will  avoid  much  of  the  annoyance  of  soiUng  caused  by 
leakage  from  cut  veins.  Thoroughly  cleanse  the  fore- 
arm and  hand  by  scraping  away  the  epithelium,  espe- 
cially from  the  palmar  surface  of  the  hand  and  fingers. 
The  finger-nails  will  usually  come  away  quite  readily, 
if  not  too  dry.  If  so,  remove  them  as  well.  The  more 
thoroughly  you  clean  the  hand  and  fingers  now,  the 
easier  your  work  will  be  when  you  dissect  them  later. 

FOREARM,   SUPERFICIAL  DISSECTION.     (See  Fig.  7.) 

Lay  the  arm  on  an  ''arm  board"  and  securely  fasten 
its  upper  end  to  the  board.  Make  a  short  longitudinal 
incision  in  the  middle  of  the  back  of  the  forearm.  Cut 
cautiously  just  through  the  skin  and  no  more.  Slightly 
retract  the  skin  on  each  side  of  the  cut  in  order  to  make 
sure  that  you  are  through  the  skin  only,  and  not 
through  the  superficial  fascia  as  well.  Then  extend 
the  incision  to  the  full  limit  above,  and  extend  it 
downwards  to  the  middle  of  the  back  of  the  wrist. 
From  this  point  make  an  incision  down  the  middle  of 


92  DISSECTION  METHODS  AND  GUIDES 

the  back  of  the  thumb  to  the  base  of  the  nail.  From 
the  same  starting-point  make  a  similar  incision  on  the 
back  of  each  finger.  Dissect  the  skin  from  the  entire 
forearm  all  the  way  down  to  the  level  of  the  wrist, 
then  cut  it  away,  with  scissors,  about  two  fingers' 
breadth  above  the  level  of  the  wrist.  When  you  come 
to  dissecting  the  palm,  you  will  realize  the  importance 
of  leaving  this  skin-flap  in  front.  Begin  on  the  back  of 
the  hand  and  dissect  off  the  skin  laterally  as  far  as  the 
'^hair  line"  on  each  side.  The  slips  of  skin  on  the 
back  of  the  hand  should  now  be  dissected  down  as 
far  as  the  webs  of  the  fingers. 

Pin  the  little  finger  down  to  the  board,  and  dissect 
skin  laterally,  as  far  around  on  the  ulnar  side  as  you 
find  it  to  be  readily  separable  from  the  underlying 
fascia.    Pin  this  skin-flap  to  the  board. 

On  the  palmar  surface  of  the  hand  and  fingers,  the 
skin  and  the  underlying  fascia  are  so  intimately  ad- 
herent that  they  are  very  difficult  to  separate.  So 
when  you  encounter  this  blending  at  the  side  of  a 
finger,  you  will  know  that  you  are  close  to  the  palmar 
surface,  and  do  not  attempt  to  effect  any  further 
separation  of  the  skin.  Reflect  the  other  half  of  the 
skin  in  the  same  manner  and  to  the  same  limit.  You 
will  find  it  necessary  to  cut  through  the  skin  laterally 
at  the  base  of  the  nail.  Repeat  this  procedure  with 
every  one  of  the  fingers  and  the  thumb.  These  skin- 
flaps  should  now  be  trimmed  away,  carefully  and 
neatly,  with  a  pair  of  scissors. 

Superficial  Veins  of  the  Forearm. — Trace  the  Ceph- 
alic Vein  downwards  from  the  arm,  and  follow  out  its 


FOREARM,  SUPERFICIAL  DISSECTION  93 

two  main  tributaries,  namely,  the  Superficial  Radial 
and  the  Median  Cephalic. 

Trace  the  Basilic  Vein  downwards  from  the  arm, 
and  follow  out  its  three  main  tributaries,  namely,  the 
Posterior  Superficial  Ulnar,  Anterior  Superficial  Ulnar, 
and  Median  Basilic. 

From  the  juncture  of  the  Median  Cephalic  Vein  and 
the  Median  Basilic  Vein  trace  downwards  the  Median 
Vein.  All  of  the  small  tributary  veins  will  have  to  be 
sacrificed,  but  the  larger  veins  can  be  divided  at  a 
low  level,  reflected  up  out  of  the  way,  and  restored 
later. 

Cutaneous  Nerves  of  the  Forearm. — Pick  up  the 
Internal  Cutaneous  Nerve  (n.  cutaneus  antebrachii 
medialis)  in  the  arm  and  trace  it  downwards  on  the 
ulnar  side  of  the  front  of  the  forearm  to  the  wrist;  then 
follow  out  the  posterior  branch  of  the  Internal  Cuta- 
neous Nerve  (m.  cutaneus  antebrachii  medialis).  Emerg- 
ing from  behind  the  outer  border  of  the  Biceps  Muscle, 
just  a  short  way  above  the  bend  of  the  elbow,  look  for 
the  Cutaneous  Branch  of  the  Musculocutaneous  Nerve. 
Follow  its  anterior  branch  downwards  on  the  radial  side 
of  the  front  of  the  forearm,  and  then  follow  its  posterior 
branch  downwards  on  the  radial  side  of  the  back  of  the 
forearm. 

Look  for  the  dorsal  branch  of  the  Ulnar  Nerve. 
You  should  find  it  just  below  the  lower  end  of  the 
Ulna,  where  it  crosses  the  tendon  of  the  Extensor  Carpi 
Ulnaris,  superficially  and  almost  at  right  angles  to  it. 
Trace  out  the  branches  of  this  nerve  on  the  back  of 
the  hand. 

On  the  radial  side,  about  the  middle  of  the  lower 


94  DISSECTION  METHODS  AND  GUIDES 

third  of  the  forearm,  look  for  the  Radial  Nerve  {ramus 
superficialis  n.  radialis),  where  it  pierces  the  deep 
fascia  after  having  crossed  backward  over  the  tendon 
of  the  Extensor  Carpi  Radialis  Brevior.  Remove  the 
fat  over  it  by  carefully  scraping  downwards,  then 
there  should  be  no  difficulty  about  seeing  the  nerve. 

Clean  the  Radial  Nerve  {ramus  superficialis  n.  radi- 
alis) and  trace  out  all  of  its  branches  except  the  Pal- 
mar Cutaneous. 

BACK   OF  THE  FOREARM  AND  HAND 

Remove  all  fat  and  ^droughly  clean  the  sheath 
of  the  forearm  and  the  Posterior  Annular  Ligament. 
Incise  the  fascia  covering  the  extensor  tendons  on  the 
backs  of  the  fingers,  carefully  expose  these  tendons 
from  the  lower  border  of  the  annular  ligament  to  their 
insertions  at  the  bases  of  the  middle  and  distal  pha- 
langes. By  making  traction  on  the  tendons  below  the 
annular  ligament,  identify  the  muscle  above.  Split 
the  deep  fascia  covering  each  muscle  on  each  side  of 
the  muscle.  In  this  fashion  identify  and  free  the 
Extensor  Communis  Digitorum.  Be  careful  not  to 
spHt  it  up  too  much;  assemble  its  tendons,  and  bind 
them  together  with  a  ligature.  Divide  the  Annular 
Ligament  over  them. 

Identify  and  free  the  Extensor  Indicis  and  the 
Extensor  Minimi  Digiti.  Expose  the  tendons  on  the 
back  of  the  thumb  from  the  annular  ligament  down 
to  their  terminations.  Lift  up  the  Extensor  Com- 
munis Digitorum;  under  it,  crossing  the  extensor 
muscles  of  the  thumb,  look  for  the  Posterior  Inter- 
osseous Branch  of  the  Musculospiral  Nerve  (n.  radialis), 


BACK  OF  THE  FOREARM  AND  HAND  95 


Fig.  7. — Back  op  Forearm  and  Hand. 
The  knife  incisions  are  indicated  by  continuous  red  lines.     When  it  has 
been  dissected  free  that  far,  the  skin  should  be  trimmed  away,  with  scissors, 
along  the  dotted  red  Unes. 


96  DISSECTION  METHODS  AND  GUIDES 

and  with  it  the  Posterior  Interosseous  Artery  (a.  inter- 
ossea  dor  sails).  Trace  both  of  them  upwards.  Free 
and  clean  the  Extensor  Ossis  Metacarpi  PoUicis  (w. 
abductor  pollicis  longus),  Extensor  Brevis  {primi  inter- 
nodii)  PoUicis,  and  the  Extensor  Longus  (secundi 
internodii)  Pollicis.  Clean  the  Anconeus  Muscle, 
retract  it  upwards  and  outwards,  and  clean  the  Re- 
current Branch  of  the  Posterior  Interosseous  Artery. 
Clean  the  Supinator  Brevis  Muscle  (m.  supinator)  y 
but  do  not  divide  it. 

Free  the  Brachioradialis  {supinator  longus),  Extensor 
Carpi  Radialis  Longior,  Extensor  Carpi  Radialis 
Brevior,  and  the  Extensor  Carpi  Ulnaris.  Trace  out 
the  Posterior  Carpal  Arch  and  Metacarpal  Arteries. 

Clean  away  all  fat  and  carefully  trim  away  all  of  the 
shreds  of  fascia  from  the  back  of  the  hand  and  fingers. 
Clean  the  Dorsalis  Pollicis  Artery  and  the  Dorsalis 
Indicis  Artery. 

Carefully  clean  the  extensor  muscles  and  remove 
all  fat  and  shreds  of  deep  fascia  that  may  have  been 
left.  The  palm  of  the  hand  must  be  dissected  before 
any  attempt  is  made  to  dissect  the  front  of  the  fore- 
arm. 

PALM   OF  THE  HAND,   SUPERFICIAL  DISSECTION 

With  the  palmar  surface  uppermost,  extend  the  fin- 
gers, spread  them  apart,  and  fasten  them  to  the  board. 
Absolutely  avoid  making  any  longitudinal  incisions  in 
the  palm  of  the  hand.  In  the  middle  of  the  palm  of 
the  hand  the  skin  and  the  palmar  fascia  are  so  in- 
timately blended  and  adherent,  that  a  longitudinal 
incision  through  them  would  greatly  increase  the 
difficulty  of  separating  them.     In  front  of  the  lower 


PALM  OF  THE  HAND,  SUPERFICIAL  DISSECTION  97 

end  of  the  forearm,  in  the  midhne,  look  for  the  Pal- 
maris  Longus  Muscle. 

Between  the  tendon  of  the  Supinator  Longus  (m. 
brachioradialis)  and  the  tendon  of  the  Flexor  Carpi 
Radialis,  look  for  the  Radial  Artery;  find  its  Super- 
ficialis  Volse  Branch;  keep  it  definitely  in  mind  in  order 
to  avoid  injuring  it.  Dissect  the  skin  downwards, 
using  as  your  guide  the  tendon  of  the  Palmaris  Longus. 
On  the  radial  side  of  the  tendon,  look  for  the  Palmar 
Cutaneous  Branch  of  the  Median  Nerve,  and  to  the 
ulnar  side  of  the  tendon,  look  for  the  Palmar  Cuta- 
neous Branch  of  the  Ulnar  Nerve.  Both  of  these  nerves 
cross  the  Anterior  Annular  Ligament  superficially. 
Dissect  the  skin  downwards  over  the  annular  liga- 
ment; follow  the  radiating  fibers  of  the  insertion  of  the 
Palmaris  Longus;  separate  the  skin  from  the  palmar 
fascia  and  its  digital  slips,  as  far  down  as  the  webs  of 
the  fingers.  In  dissecting  the  skin  from  the  Thenar 
Eminence,  be  careful  not  to  cut  the  Superficialis  Volae 
Artery. 

In  removing  the  skin  from  the  Hypothenar  Emi- 
nence, do  not  at  the  same  time  remove  any  of  the  under- 
lying, hard  granular  fat.  Trim  the  skin  away  at  the 
bases  of  the  thumb  and  fingers,  with  a  pair  of  scissors. 

By  pressing  on  the  palmar  fascia,  you  can  usually 
cause  much  soft  fat  to  well  up  between  the  digital  slips. 
With  a  pair  of  scissors,  ''curved  on  the  flat,"  carefully 
trim  away  as  much  of  this  fat  as  will  readily  protrude. 
Removal  of  this  fat  now,  will  make  the  later  stages  of 
the  dissection  very  much  easier  to  do.  Make  a  mid- 
hne incision  down  the  entire  length  of  the  little  finger. 
Cut  deeply  enough  to  expose  the  theca  of  the  flexor 


98  DISSECTION  METHODS  AND  GUIDES 

tendons  and  to  divide  the  dense  fibrous  tissue  that 
covers  in  the  Digital  Nerves  and  Arteries.  Reflect 
this  dense  deep  fascia  and  the  skin,  at  the  same  time, 
toward  the  ulnar  side.  Embedded  in  the  soft  fat  at 
the  side  of  the  finger,  look  for  the  Digital  Nerve,  free 
it,  and  trace  it  up  to  its  origin  from  the  Ulnar.  At  the 
side  of  the  finger,  lying  behind  the  nerve,  look  for  the 
Digital  Artery  and  trace  it  upwards  to  its  origin  from 
the  Superficial  Palmar  Arch.  This  nerve  and  artery, 
on  the  ulnar  side  of  the  little  finger,  are  especially  liable 
to  be  cut  when  the  hypothenar  fat  is  being  removed; 
so  it  is  important  to  trace  them  out  fully  before  at- 
tempting to  remove  that  fat. 

Reflect  the  skin  and  deep  fascia  laterally  from  the 
other  half  of  the  little  finger.  You  will  find  the  nerve 
and  artery  in  the  same  relative  position  on  this  side 
that  they  were  on  the  other  side.  Trace  both  upwards 
to  where  they  dip  in  between  the  digital  slips  of  the 
palmar  fascia.  Dissect  the  other  fingers  in  exactly 
the  same  way  that  you  have  used  for  the  little  finger. 
Then  carefully  and  neatly  trim  away  all  of  the  lateral 
skin-flaps.  Clean  the  Palmaris  Brevis  Muscle,  reflect 
it  toward  the  midline  of  the  hand,  but  do  not  detach 
it  from  the  palmar  fascia.  With  flat  curved  scissors, 
carefully  trim  away  all  of  the  hard,  granular  hypo- 
thenar fat,  clean  the  surface  of  the  Hypothenar  Mus- 
cles, but  do  not  attempt  to  separate  them  at  this  time. 
Find  the  Superficialis  Volse  Artery,  above  the  wrist, 
and  trace  it  downwards.  If  you  find  it  piercing  the 
Abductor  Pollicis  or  passing  under  that  muscle,  cease 
following  it  for  the  time  being.  If  it  is  superficial, 
follow  it  to  its  termination.    Clean  the  surface  of  the 


PALM  OF  THE  HAND,  SUPERFICIAL  DISSECTION 


99 


Fig.  S. — Front  of  Right  Forearm  and  Palm  op  Hand. 
The  only  knife  incisions  to  be  made  are  indicated  by  continuous  red  lines. 
The  red  dotted  lines  indicate  where  the  skin  is  to  be  trimmed  away  with 
scissors. 


100  DISSECTION  METHODS  AND  GUIDES 

Thenar  Muscles,  but  do  not  separate  them  in  any 
way.  Incise  the  palmar  surface  of  the  thumb  in  the 
same  way  that  you  did  the  fingers.  Trace  the  nerves 
back  to  the  palm  of  the  hand  and  trace  the  arteries 
back  to  the  Princeps  PoUicis.  Trim  away  the  lateral 
skin-flaps. 

Divide  the  Anterior  Annular  Ligament  on  the  radial 
side  of  the  tendon  of  the  Palmaris  Longus.  Divide 
the  digital  slips  and  reflect  the  palmar  fascia  upwards. 
Clean  the  Superficial  Palmar  Arch  (arcus  volaris 
superficialis)  and  all  of  its  branches.  Lift  up  the 
Median  Nerve  and  clean  all  of  its  branches. 

Split  open  all  of  the  sheaths  of  the  flexor  tendons, 
so  that  the  tendons  can  be  lifted  up  and  the  deep 
tendons  separated  from  the  superficial  tendons.  De- 
fer the  deep  dissection  of  the  hand  until  the  front  of 
the  forearm  has  been  dissected. 

FRONT  OF  THE  FOREARM,  DEEP  DISSECTION 

The  nerves  and  arteries  are  the  structures  most 
likely  to  be  destroyed,  therefore  they  should  be  care- 
fully isolated  before  any  attempt  is  made  at  cleaning 
the  muscles.  In  order  to  allow  ready  access  to  the 
nerves  and  arteries,  the  muscles  will  have  to  be  sepa- 
rated and  thoroughly  loosened  up  so  that  they  can  be 
lifted  up  and  freely  retracted.  For  this  reason  the 
hand  should  be  dissected  first,  and  the  anterior  annu- 
lar ligament  should  be  divided  before  attacking  the 
deep  structures  in  the  front  of  the  forearm. 

Lift  up  the  tendon  of  the  Palmaris  Longus;  on  each 
side  of  its  muscular  belly,  split  the  Deep  Fascia  that 
constitutes  the  sheath  of  the  forearm,  and  free  the 


FRONT  OF  THE  FOREARM,  DEEP  DISSECTION  101 

muscle  with  your  finger.  Free  the  Flexor  Carpi 
Ulnaris,  Flexor  Carpi  RadiaUs,  and  the  Brachio- 
radialis.  In  each  instance,  lift  up  the  tendon  and  free 
the  muscle  with  your  finger.  Lastly,  free  the  Pro- 
nator Radii  Teres  and  trim  away  the  Bicipital  (Semi- 
lunar) Fascia. 

It  will  be  necessary  to  sacrifice  the  arteries  that 
supply  these  muscles;  so  snip  them  off,  close  to  the 
muscle  they  enter. 

Thoroughly  clean  the  Radial  Artery  and  remove  its 
Venae  Comites.  Follow  the  Radial  Recurrent  Artery, 
along  with  the  Musculospiral  Nerve,  upwards  between 
the  Brachioradialis  Muscle  and  the  Brachialis  Anticus, 
to  its  anastomosis  with  the  Superior  Profunda  Branch 
of  the  Brachial  Artery. 

Thoroughly  clean  the  superficial  layer  of  muscles, 
remove  their  sheaths,  and  all  of  the  intermuscular 
areolar  tissue  and  fat. 

Clean  the  two  heads  of  the  Flexor  Carpi  Ulnaris; 
be  careful  of  the  Ulnar  Nerve  and  Posterior  Ulnar 
Recurrent  Artery  which  pass  through  the  interval. 
Clean  the  two  heads  of  the  Pronator  Radii  Teres  and 
free  the  Median  Nerve  as  it  passes  between  them. 
Clean  the  middle  and  outer  heads  of  the  Flexor  Sub- 
limis  Digitorum  and  carefully  free  the  intervening 
border  of  the  muscle.  Clean  the  superficial  surface  of 
the  Flexor  Sublimis,  assemble  its  tendons  and  tie  them 
together,  lift  it  up,  and  thoroughly  free  it  with  your  fin- 
ger from  the  underlying  muscles.  Do  not  divide  the 
Flexor  Sublimis  in  any  way.  It  is  only  necessary  to 
flex  the  fingers  and  wrist  in  order  to  relax  it  fully. 
Carefully  preserve  the  arch  formed  by  its  upper  border. 


102  DISSECTION  METHODS  AND  GUIDES 

Retract  the  Flexor  Sublimis  toward  the  radial  side. 
Clean  the  Ulnar  Nerve  and  follow  it  up  into  the  arm. 
Be  careful,  in  the  region  of  the  elbow,  not  to  cut  the 
Posterior  Ulnar  Recurrent  or  Inferior  Profunda  {a. 
collateralis  ulnaris  superior)  Arteries,  which  you  will 
find  with  that  part  of  the  Ulnar  Nerve. 

Clean  the  Ulnar  Artery  and  remove  its  Venae 
Comites;  the  muscular  branches  will  have  to  be  sac- 
rificed. 

Antecubital  Space. — Retract  the  Pronator  Radii 
Teres  downwards.  Clean  the  Anterior  Ulnar  Recur- 
rent Artery  and  follow  it  up  to  the  Anastomotica 
Magna  (a.  collateralis  ulnaris  inferior).  Clean  the 
Common  Interosseous  Artery  and  the  commencement 
of  the  Posterior  Ulnar  Recurrent  Artery. 

Clean  the  insertions  of  the  Biceps  and  Brachialis 
Anticus  (m.  hrachialis).  Remove  all  of  the  debris  and 
fat,  and  thoroughly  clean  up  the  Antecubital  Space. 

Reflect  the  Flexor  Sublimis  toward  the  radial 
side;  finish  cleaning  the  Posterior  Ulnar  Recurrent 
Artery  and  follow  it  upwards  to  its  anastomosis  with 
the  Inferior  Profunda  (a.  collateralis  ulnaris  superior). 
Finish  cleaning  the  Median  Nerve. 

Assemble  the  tendons  of  the  Flexor  Profundus 
Digitorum,  tie  them  together,  and  then  clean  that 
muscle  and  the  Flexor  Longus  PoUicis. 

Separate  these  two  muscles,  and  clean  the  Anterior 
Interosseous  Artery  and  the  Anterior  Interosseous 
Branch  of  the  Median  Nerve. 

Clean  the  Pronator  Quadratus  Muscle  and  the 
Anterior  Carpal  Branches  of  the  Radial  and  Ulnar 
Arteries. 


THE  HAND,  DEEP  DISSECTION  103 

THE  HAND,  DEEP  DISSECTION 

Pick  up  the  tendons  of  the  Flexor  Profundus  Digi- 
torum  and  clean  the  Lumbricales  Muscles. 

Locate  the  base  of  the  proximal  phalanx  of  the  little 
finger.  On  its  ulnar  side,  you  will  find  the  insertion  of 
two  tendons.  Lift  both  of  these  up  together  and  sepa- 
rate their  muscles  from  the  underlying  Opponens 
Minimi  Digiti  (m.  opponens  digiti  quinti).  Use  your 
knife  handle  for  doing  this. 

Now  separate  the  two  tendons  from  each  other,  and 
working  upwards,  separate  the  Abductor  Minimi  Digiti 
(w.  abductor  digiti  quinti)  from  the  underlying  Flexor 
Brevis  Minimi  Digiti  (m.  flexor  digiti  quinti  hrevis). 
In  the  interval  between  them,  look  for  the  deep  palmar 
branches  of  the  Ulnar  Artery  and  Ulnar  Nerve. 

The  Thenar  Muscles. — Separate  the  Abductor  Pol- 
licis  from  the  underlying  Opponens  and  Flexor  Brevis. 
Be  careful  not  to  injure  the  Superficial  Volar  Artery. 

Retract  the  Abductor  Pollicis  (m.  abductor  pollicis 
brevis)  upwards;  separate  the  Opponens  (or  Flexor 
Ossis  Metacarpi)  PolUcis  from  the  Flexor  Brevis  Pol- 
hcis  and  free  it  thoroughly. 

Locate  the  base  of  the  proximal  phalanx  of  the 
thumb.  On  its  ulnar  side,  you  will  find  the  insertion 
of  two  flat  tendons.  The  more  superficial  and  ante- 
rior one  of  them,  is  the  insertion  of  the  inner  head 
(Adductor  Obhquus)  of  the  Flexor  Brevis.  The 
deeper  and  more  posterior  insertion,  is  that  of  'the 
Adductor  (Adductor  Transversus)  Pollicis. 

By  separating  their  insertions,  it  becomes  easy  to 
separate  the  Adductor  Pollicis  from  the  Flexor  Brevis. 
Separate  the  Adductor  PolHcis  from  the  Interosseous 


104  DISSECTION  METHODS  AND  GUIDES 

Muscles  behind  it.  The  two  heads  of  the  Flexor 
Brevis  are  easily  separated. 

Clean  the  Princeps  PoUicis  Artery  and  the  Radialis 
Indicis  Artery. 

Follow  the  Radial  Artery,  between  the  two  heads 
of  the  First  Dorsal  Interosseous  Muscle,  into  the  palm 
of  the  hand,  and  clean  the  Deep  Palmar  Arch  and  its 
branches. 

Remove  all  fat  and  clean  the  Interosseous  Muscles. 


LOWER  EXTREMITY 

Order  of  Dissections 

1.  Gluteal  Region. 

2.  Back  of  the  Thigh. 

3.  Popliteal  Space. 

4.  Back  of  the  Leg. 

5.  Sole  of  the  Foot. 

6.  Front  of  Thigh,  superficial  dissection. 

7.  Front  and  Inner  Side  of  the  Thigh,  deep  dissection. 

8.  Front  of  the  Leg  and  Dorsum  of  Foot. 

GLUTEAL  REGION 

Thoroughly  clean  the  surface  of  this  region  and 
scrape  away  loose  epithelium.  Make  an  incision  from 
the  tip  of  the  coccyx,  downwards  and  outwards,  to  a 
point  just  below  the  attachment  of  the  Gluteus  Maxi- 
mus  (w.  glutceus  maximus)  to  the  femur.  Make  a 
second  incision  from  the  tip  of  the  coccyx,  up  the 
midline  of  the  back,  to  a  point  on  a  level  with  the 
crest  of  the  ilium,  and  from  thence,  laterally  outwards, 
following  the  outline  of  the  crest,  to  the  anterior 
superior  spine  of  the  ilium.  Begin  at  the  middle  of  the 
sacrum  and  reflect  the  skin  forwards  and  downwards 
without  trying  to  remove  much  fat.  Beginning  at  the 
same  place,  cautiously  reflect  the  fatty  layer  of  the 
superficial  fascia  in  the  same  manner  as  the  skin. 
As  you  advance,  be  on  the  watch  for  the  cutaneous 
nerves,  which  you  will  find  as  follows: 

Piercing  the  Deep  Fascia,  immediately  above  and  in 
front  of  the  iliac  attachment  of  the  Gluteus  Maximus 

105 


106  DISSECTION  METHODS  AND  GUIDES 

(m.  glutceus  maximus),  look  for  the  Iliac  Branch  of  the 
Iliohypogastric  Nerve,  it  runs  almost  vertically  down- 
wards. 

Piercing  the  Deep  Fascia,  slightly  behind  and  lower 
than  the  Iliac,  look  for  the  Posterior  Branches  of  the 
Lumbar  Nerves,  they  run  downwards  and  slightly 
outwards. 

Piercing  the  Deep  Fascia,  close  to  the  sacral  origin 
of  the  Gluteus  Maximus  (m.  glutceus  maximus),  look  for 
the  Posterior  Branches  of  the  Sacral  Nerves.  They 
are  three  in  number,  and  run  horizontally  outwards. 

Winding  upwards  from  under  the  postero-inferior 
border  of  the  Gluteus  Maximus  (m.  glutceus  maximus), 
look  for  the  Perforating  Cutaneous  Branch  of  the 
Fourth  Sacral  Nerve.  After  perforating  the  Great  Sac- 
rosciatic  Ligament  (/.  sacrotuberosum) ,  it  curls  around 
the  lower  border  of  the  Gluteus  Maximus,  and  then 
runs  almost  vertically  upwards. 

Remove  all  of  the  fatty  layer.  Thoroughly  clean  the 
surface  of  the  Gluteus  Maximus  (m.  glutceus  maximus) 
and  remove  its  sheath.  The  easiest  way  of  doing  this 
is  to  use  a  pair  of  scissors  (''curved  on  the  flat"), 
and  work  from  above  and  behind  toward  the  femoral 
insertion.  Be  particularly  careful  to  clearly  define 
both  borders  of  the  Gluteus  Maximus  (m.  glutceus 
maximus),  especially  the  postero-inferior  border.  With 
your  fingers,  thoroughly  free  the  Gluteus  Maximus 
from  the  underlying  structures,  and  then  divide  it, 
from  before  backwards,  at  the  level  of  the  top  of  the 
Great  Trochanter  of  the  Femur.  Reflect  the  lower 
portion  downwards.  Note  the  bursa  between  it  and 
the  Great  Trochanter. 


Fig.  9. — Gluteal  Region,  Back  of  Thigh,  Popliteal  Space,  and  Back 

OP  Leg. 

Continuous  red  lines  indicate  knife  incisions.     Dotted  red  lines  show  where 

the  skin  should  be  cut  with  scissors  only, 

107 


108  DISSECTION  METHODS  AND  GUIDES 

Reflect  the  upper  portion  upwards.  Note  the  bursa 
between  it  and  the  tuberosity  of  the  ischium.  Carefully 
detach  the  Gluteus  from  the  Great  Sacrosciatic  Liga- 
ment.    Be  careful  of  the  Perforating  Cutaneous  Nerve. 

Entering  the  deep  surface  of  the  Gluteus  Maximus 
(m.  glutoeus  maximus)  you  will  find  the  superficial 
branches  of  the  Gluteal  (a.  glutcea  superior)  Branch  of 
the  Posterior  Division  of  the  Internal  Iliac  Artery,  the 
Inferior  Gluteal  (n.  glutwus  inferior)  Branch  of  the 
Sacral  Plexus,  and  the  Gluteal  (nn.  clunium  inferior es 
[laterales])  Branches  of  the  Small  Sciatic  (n.  cutaneus 
femoris  posterior)  Nerve  from  the  Sacral  Plexus. 

Carefully  clean  the  surface  of  the  Great  Sacrosciatic 
Ligament  (/.  sacrotuberosum)  and  the  deep  surface  of 
the  Gluteus  Maximus  (m.  glutoeus  maximus). 

Carefully  define  the  Great  Sacrosciatic  Foramen  and 
isolate  the  structures  that  emerge  from  it,  without 
trying  as  yet  to  clean  them.  You  will  find  the  Super- 
ficial Branch  of  the  Gluteal  Artery  (a.  glutcea  superior) 
running  upwards.    Clean  it. 

Radiating  forwards,  and  forwards  and  upwards,  are 
the  Deep  Branches  of  the  Gluteal  Artery  (a.  glutcea 
superior)  and  the  Superior  Gluteal  (n.  glutoeus  superior) 
Branch  of  the  Lumbosacral  Cord. 

Running  directly  downwards  you  will  find  the  Great 
Sciatic  (n.  ischiadicus)  Branch  of  the  Sacral  Plexus. 
To  its  inner  side,  and  then  crossing  behind  to  gain  its 
outer  side,  you  will  find  the  Small  Sciatic  {n.  cutaneus 
femoris  posterior)  Branch  of  the  Sacral  Plexus,  accom- 
panied by  the  Sciatic  Vessels  {vasa  nervi  comes  ischiatici) . 
Using  a  pair  of  scissors  (^^curved  on  the  flat"),  carefully 
trim  away  all  of  the  fat  and  areolar  tissue;  thoroughly 


GLUTEAL  REGION  109 

clean  the  Gluteus  Medius   (m.   glutoeus  medius)   and 
remove  its  sheath. 

In  freeing  the  anterior  border  of  the  Gluteus  Medius 
(m.  glutceus  medius),  split  the  Deep  Fascia  along  the 
posterior  border  of  the  Tensor  Vaginae  (Fascia)  Femoris, 
but  be  careful  not  to  divide  the  nerve  to  the  Tensor 
as  it  emerges  from  under  the  Gluteus  Medius.  Free 
the  Gluteus  Medius,  divide  it  close  to  its  insertion, 
and  reflect  it  upwards.  Entering  its  deep  surface,  you 
will  find  the  branches  of  the  Superior  Gluteal  Nerve 
(from  the  Lumbosacral  Cord)  and  Deep  Branches  of 
the  Gluteal  Artery  (Branch  of  the  Posterior  Division 
of  the  Internal  Iliac) ,  the  main  trunks  of  which  emerge 
from  between  the  Pyriformis  and  Gluteus  Minimus, 
and  lie  on  the  surface  of  the  Gluteus  Minimus.  First 
clean  the  nerve  and  artery,  then  the  deep  surface  of 
the  Gluteus  Medius,  the  Gluteus  Minimus,  and  the 
Pyriformis.  Carefully  free  the  Pyriformis  from  the 
Gluteus  Minimus  and  the  Gemellus  Superior.  Fre- 
quently the  peroneal  portion  of  the  Great  Sciatic 
Nerve  (n.  ischiadicus)  pierces  the  Pyriformis,  while 
the  tibial  portion  emerges  separately  from  underneath 
the  Pyriformis.  Emerging  from  between  the  Pyri- 
formis and  the  Gemellus  Superior  are  the  following 
structures,  which  should  be  cleaned  in  the  order  given : 

Inferior  Gluteal  Nerve  (branch  of  Sacral  Plexus); 
Sciatic  Artery  (Branch  of  the  Anterior  Division  of  the 
Internal  Iliac);  Small  Sciatic  Nerve  (from  Sacral 
Plexus).  You  will  find  its  Long  Pudendal  Branch 
running  inwards  across  the  back  of  the  Hamstring 
Muscles  just  below  their  origin  from  the  Tuberosity  of 
the  Ischium;  the  Great  Sciatic  Nerve  (n.  ischiadicus); 


110  DISSECTION  METHODS  AND  GUIDES 

lastly,  crossing  the  Spine  of  the  Ischium  and  Lesser 
Sacrosciatic  Ligament  (I.  sacrospinosum) ,  you  will 
find  in  the  following  order,  from  within  outwards;  the 
Pudic  Nerve  (n.  pudendalis)  from  Sacral  Plexus,  the 
Internal  Pudic  (a.  pudenda  internis)  Branch  of  the 
Anterior  Division  of  the  Internal  Iliac  Artery,  and  the 
nerve  to  the  Obturator  Internus  (from  the  Sacral 
Plexus). 

Clean  merely  the  exposed  portions  of  the  Pudic 
Nerve  and  Artery  and  the  nerve  to  the  Obturator 
Internus,  and  be  sure  not  to  cut  the  Great  Sacrosciatic 
Ligament  (1.  sacrotuberosum)  for  any  purpose  what- 
ever. Clean  and  separate  from  each  other  the  Gamel- 
lus  Superior,  Obturator  Internus,  Gamellus  Inferior, 
and  the  Quadratus  Femoris. 

BACK  OF  TfflGH 

Make  an  incision  down  the  middle  of  the  back  of 
the  thigh  to  a  point  a  hand's  breadth  below  the  bend 
of  the  knee.  From  this  incision  reflect  the  skin  laterally, 
on  the  outer  side,  as  far  as  the  Tensor  Vaginae  Femoris, 
and  on  the  inner  side,  as  far  as  the  Gracilis.  At  the 
lower  end  of  the  incision,  cut  the  skin  laterally  with 
scissors.  Do  not  make  any  knife-incisions  around  the 
leg.  Pick  up  the  Small  Sciatic  Nerve  (n.  cutaneus 
femoris  posterior),  split  the  overlying  fascia  with  a 
pair  of  blunt-pointed  scissors;  follow  this  nerve  down- 
wards and  trace  out  each  of  its  lateral  branches  as  you 
come  to  it. 

Now  reflect  the  fascia  and  overlying  fat  laterally,  as 
far  as  the  reflection  of  the  skin,  and  trim  it  away. 
Free  the  lower  border  of  the  Quadratus  Femoris  from 


BACK  OF  THIGH  111 

the  Adductor  Magnus.  Emerging  from  between  them, 
you  will  find  the  Internal  Circumflex  (a.  circumflexa 
femoris  medialis)  Branch  of  the  Profunda  Femoris 
Artery.  Thoroughly  free  the  Quadratus  Femoris,  with 
your  finger,  from  the  underlying  structures,  and  rotate 
the  Femur  outward  in  order  to  relax  it. 

Clean  the  Internal  Circumflex  Artery  (a.  circum- 
flexa femoris  medialis),  trace  its  transverse  branch 
outwards  to  where  it  anastomoses  with  the  terminal 
branches  of  the  External  Circumflex,  on  the  outer 
side  of  the  Great  Trochanter  of  the  Femur.  It  is 
joined  from  above  by  the  Sciatic  Artery,  and  from 
below  by  the  Superior  Perforating  Branch  of  the 
Profunda  Femoris,  forming  what  is  known  as  the 
Crucial  Anastomosis.  Retract  the  Quadratus  Femoris 
and  clean  the  underlying  tendon  of  the  Obturator 
Externus,  the  upper  border  of  the  Adductor  Magnus 
Muscle,  and  the  deep  surface  of  the  Quadratus.  Op- 
posite the  insertion  of  the  Gluteus  Maximus,  look 
for  the  Superior  Perforating  Artery  (a.  perforans 
prima),  as  it  pierces  the  Adductor  Magnus  close  to 
its  femoral  attachment. 

Clean  this  artery  and  trace  it  upwards  to  the  Crucial 
Anastomosis.  Thoroughly  free  and  clean  the  Long 
Head  of  the  Biceps,  the  Semitendinosus,  and  the  Semi- 
membranosus Muscles.  Clean  the  main  trunk  of  the 
Great  Sciatic  Nerve.  Pull  the  Long  Head  of  the  Biceps 
aside  and  look  for  the  lower  three  Perforating  (aa. 
perforantes)  Branches  of  the  Profunda  Femoris.  They 
pierce  the  Adductor  Magnus  close  to  its  femoral  at- 
tachment opposite  the  origin  of  the  Short  Head  of  the 
Biceps. 


112  DISSECTION  METHODS  AND  GUIDES 

Be  especially  careful  of  the  lowermost  one,  the 
Inferior  Perforating,  but  do  not  attempt  to  follow  it 
out  until  you  dissect  the  Popliteal  Space. 

Clean  both  sides  of  the  Short  Head  of  the  Biceps  and 
the  entire  posterior  surface  of  the  Adductor  Magnus. 
Thoroughly  remove  all  areolar  tissue  and  fat. 

POPLITEAL  SPACE 

Make  an  incision  down  the  middle  of  the  back  of 
the  leg  to  the  point  of  the  heel.  From  this  incision 
reflect  the  skin  laterally  far  enough  to  fully  expose  the 
back  of  the  leg.  On  the  outer  side  of  the  Tendo  Achillis, 
look  for  the  External  (or  Short)  Saphenous  Vein,  ac- 
companied along  its  outer  side  by  the  Exterjial  (or 
Short)  Saphenous  Nerve.  Follow  the  vein  upwards  to 
where  it  pierces  the  Deep  Fascia  to  enter  the  Popliteal 
Space,  split  the  fascia  over  it  with  blunt-pointed 
scissors,  and  follow  it  to  the  Popliteal  Vein.  As  you 
trace  the  external  Saphenous  Nerve  upwards  you  will 
find  that  it  arises  from  two  heads.  The  inner  head 
(Communicans  Tibialis)  will  lead  to  the  Internal  Pop- 
liteal Nerve.  The  outer  head  is  the  Communicans 
Fibularis  (or  Peronei).  After  piercing  the  Deep  Fascia 
below  and  further  out  than  does  the  inner  head,  it 
leads  to  the  External  Popliteal  (or  Peroneal)  Nerve. 

Trace  the  Communicans  Fibularis  upwards  to  the 
External  Popliteal  Nerve;  then  trace  it  downwards 
through  the  Deep  Fascia  on  to  the  outer  side  of  the 
back  of  the  leg.  Clean  the  surface  of  both  of  the  heads 
of  the  Gastrocnemius  Muscle,  but  do  not  divide  either 
of  them,  and  be  careful  not  to  tear  them  apart  where 
they  join  together  to  form  the  main  muscle.    Free  with 


POPLITEAL  SPACE  113 

your  finger  the  tendons  of  the  Hamstring  Muscles. 
Just  above  the  origin  of  each  of  the  heads  of  the  Gas- 
trocnemius from  the  condyles  of  the  femur,  feel  in 
the  loose  areolar  tissue  and  fat  for  the  Superior  Articu- 
lar Arteries,  tear  the  areolar  tissue  away  with  your 
forceps  and  expose  these  arteries,  but  do  not  attempt 
to  work  them  out  as  yet. 

Using  your  fingers,  free  the  heads  of  the  Gastroc- 
nemius from  the  underlying  structures,  but  be  care- 
ful not  to  tear  in  two  the  Sural  Artery  which  enters 
the  deep  surface  of  each.  Free  the  Plantaris  Muscle 
and  then  free  the  united  portion  of  the  Gastrocne- 
mius from  the  Soleus.  Isolate  the  Tendon  of  the 
Plantaris. 

Divide  the  Gastrocnemius  well  below  the  union  of 
its  two  heads  in  order  to  preserve  the  arch  they  form. 
Be  careful  not  to  divide  the  Tendon  of  the  Plantaris. 
Reflect  the  Gastrocnemius  upwards  and  isolate  the 
Sural  Artery  and  the  muscular  branch  of  the  Internal 
Popliteal  Nerve,  which  you  will  find  entering  the 
deep  surface  of  each  head.  On  the  back  of  the  inner 
tuberosity  of  the  tibia,  feel  for  the  Inferior  Internal 
Articular  Artery.  It  runs  inwards  and  downwards  from 
the  midline  of  the  back  of  the  knee.  Isolate  it,  but  do 
not  yet  attempt  to  trace  it  out.  On  the  back  of  the 
outer  tuberosity  of  the  tibia,  just  above  the  head  of 
the  fibula,  look  for  the  External  Inferior  Articular 
Artery.  Expose  it  without  tracing  it  out.  Clean  and 
clearly  define  the  arch  formed  by  the  upper  border  of 
the  Soleus  Muscle,  and  free  it  with  your  finger  from 
the  underlying  structures.  Isolate  the  Internal  Pop- 
liteal Nerve  and  its  branches  in  the  Popliteal  Space 


114  DISSECTION  METHODS  AND  GUIDES 

and  clean  it  as  far  as  the  arch  formed  by  the  upper 
border  of  the  Soleus.  In  the  same  way  clean  the  Pop- 
liteal Vein.  Clean  the  External  Popliteal  Nerve  and 
follow  it  outwards  to  where  it  passes  under  the  Tendon 
of  the  Biceps.  Clean  the  Plantaris  Muscle.  Remove 
the  Sheath  of  the  Popliteal  Artery.  Clean  the  Superior 
Internal  Articular  Artery  and  follow  it  to  where  it 
passes  under  the  Tendon  of  the  Adductor  Magnus. 
Clean  the  Internal  Sural  Artery  and  the  Inferior 
Internal  Articular  Artery.  Clean  the  Superior  Ex- 
ternal Articular  Artery  and  follow  it  to  where  it  passes 
under  the  Tendon  of  the  Biceps.  Clean  the  Azygos 
Articular,  External  Sural,  and  Inferior  External  Articu- 
lar Arteries. 

Thoroughly  remove  all  of  the  areolar  tissue  and  fat 
from  the  Popliteal  Space,  scrape  it  away  from  the  back 
surface  of  the  Femur.  Clean  the  Biceps  Tendon  and 
the  External  Lateral  Ligament  of  the  knee.  Clean 
the  surface  of  the  Posterior  Ligament  of  the  Knee, 
especially  the  portion  that  runs  from  the  outer  con- 
dyle obliquely  downwards  and  inwards  to  the  Inner 
Tuberosity  of  the  Tibia  (Winslow's  Ligament).  Clean 
the  Tendon  of  the  Semimembranosus  and  trace  its 
continuation  into  Winslow's  Ligament.  Clean  the 
exposed  surface  of  the  Popliteus  Muscle  and  remove 
the  fat  from  the  Arch  of  the  Soleus. 

BACK  OF  LEG,   DEEP  DISSECTION 

It  is  not  necessary  to  have  the  body  in  a  prone  posi- 
tion. By  flexing  the  knee  and  rotating  the  thigh  this 
region  can  be  got  at  very  readily. 

Clean  the  lower  portion  of  the  Gastrocnemius,  the 


BACK  OF  LEG,  DEEP  DISSECTION  115 

Tendo  Achillis,  and  the  Tendon  of  the  Plantaris. 
Reflect  the  lower  portion  of  the  Gastrocnemius  down- 
wards. Clean  its  deep  surface  and  the  superficial  sur- 
face of  the  Soleus.  Free  with  your  finger  the  Tendo 
Achillis  and  the  lower  part  of  the  Soleus  from  the 
underlying  structures.  Do  not  divide  the  Soleus,  but, 
beginning  from  below,  detach  it  from  the  Tibia  all  the 
way  up,  except  the  uppermost  portion,  which  should 
be  retained  in  order  to  preserve  the  aponeurotic 
arch  of  the  upper  border  of  the  Soleus.  In  the  same 
way  detach  the  lower  part  of  the  Soleus  from  the  Shaft 
of  the  Fibula,  but  do  not  divide  it  anywhere.  Reflect 
the  Soleus  outwards  and  remove  the  underlying  deep 
fascia. 

Clean  the  Posterior  Tibial  Nerve  and  Posterior 
Tibial  Artery.  Some  of  the  small  muscular  branches 
of  the  artery  will  have  to  be  cut.  Finish  the  cleaning 
of  the  Popliteus  Muscle.  Retract  the  Soleus  inwards. 
Clean  the  commencement  of  the  Anterior  Tibial  Artery 
and  the  commencement  of  the  Peroneal  Artery.  Re- 
move the  Deep  Fascia  overlying  the  Flexor  Longus 
Hallucis.  Clean  the  Peroneus  Longus  and  the  surface 
of  the  Flexor  Longus  Hallucis.  Retract  the  Soleus 
outwards,  free  the  inner  border  of  the  Flexor  Longus 
Hallucis,  lift  it  up  and  finish  cleaning  the  Peroneal 
Artery. 

Clean  the  surface  of  the  Flexor  Longus  Digitorum, 
free  it  from  the  underlying  Tibialis  Posticus,  retract 
it  inwards  and  clean  its  deep  surface  and  the  surface 
of  the  Tibialis  Posticus. 

Incise  the  skin  and  reflect  it  forwards  far  enough 
to  expose  the  inner  side  of  the  ankle. 


116  DISSECTION  METHODS  AND  GUIDES 

Carefully  clean  the  Internal  Annular  Ligament 
behind  the  Internal  Malleolus. 

Remove  all  of  the  fat  from  under  the  Tendo  Achillis. 
Note  the  bursa  between  it  and  the  Calcaneum. 

THE  SOLE  OF  THE  FOOT 

While  it  is  not  absolutely  necessary  to  have  the  body 
in  a  prone  position,  the  sole  of  the  foot  is  far  easier 
to  dissect  when  the  heel  is  uppermost.  The  foot  and 
toes  should  be  thoroughly  cleaned  by  scraping  away 
the  epithelium  from  the  plantar  surface  especially, 
and  the  toe-nails  should  be  removed  if  they  are  loose. 

Pinch  up  the  pad  on  the  plantar  surface  of  the  heel 
in  order  to  acquaint  yourself  with  its  thickness.  By 
doing  so  you  can  readily  determine  the  level  at  which 
your  incision  should  be  made,  in  order  to  completely 
remove  the  pad  from  the  calcaneum.  Commence  your 
skin  incision  on  the  side  of  the  base  of  the  little  toe, 
carry  it  backwards  along  the  outer  side  of  the  foot, 
then  around  the  back  of  the  heel,  then  along  the  inner 
side  of  the  foot,  following  the  contour  of  the  instep, 
then  over  the  side  of  the  ball  of  the  great  toe  as  far  as 
the  plantar  crease  of  the  toes.  Longitudinal  incisions 
in  the  sole  of  the  foot  should  be  avoided  absolutely. 

Nor  should  the  skin  ever  be  cut  transversely  except 
with  scissors,  and  then,  only  at  the  level  of  the  web  of 
the  toes  after  it  has  been  dissected  forwards  to  that 
point.  It  is  a  great  disadvantage  to  attempt  dissecting 
the  skin  towards  the  heel.  Any  knife  incision  in  the 
sole  of  the  foot,  not  only  endangers  important  struc- 
tures, but  is  very  likely  to  more  than  double  the  diffi- 
culty of  subsequent  dissection.     Begin  in  the  incision 


THE  SOLE  OF  THE  FOOT 


117 


Fig.  10. — Sole  op  the  Foot. 
The  knife  incisions  are  indicated  by  continuous  red  lines.     After  it  has 
been  dissected  up  that  far,  the  skin  should  be  trimmed,  with  scissors,  along 
the  dotted  red  lines. 


118  DISSECTION  METHODS  AND  GUIDES 

on  the  back  of  the  heel  and  cut  forwards  boldly  to  the 
bone;  then  continue  forwards  along  the  plantar  surface 
of  the  calcaneum  until  you  encounter  the  bursa.  The 
bursa  can  be  readily  recognized  by  its  glistening 
surface.  Follow  this  surface  forwards  and  it  will  lead 
to  the  Plantar  Fascia  (aponeurosis  plantaris).  Follow 
the  plane  of  the  Plantar  Fascia  forwards  until  you 
encounter  its  digital  sUps.  Keep  superficial  to  these 
digital  slips  and  follow  each  of  them  all  the  way  to  the 
web  of  the  toes.  Trim  away  this  flap  with  a  pair  of 
scissors.  If  you  have  been  careful  to  always  keep 
superficial  to  the  Plantar  Fascia  and  its  digital  pro- 
ductions, this  plantar  flap  will  consist  merely  of  skin 
and  fat,  and  cannot  possibly  contain  any  important 
structure. 

Thoroughly  clean  the  exposed  surface  of  the  Plan- 
tar Fascia  (aponeurosis  plantaris).  Much  soft  fat  will 
now  protrude  between  the  digital  slips  of  the  Plan- 
tar Fascia.  Trim  this  away  with  a  pair  of  scis- 
sors ''curved  on  the  flat."  Press  on  the  digital  sUps 
with  the  convex  side  of  the  open  scissors,  and  cut 
away  as  much  of  this  fat  as  can  readily  be  made  to 
protrude.  Since  the  digital  vessels  and  nerves  lie  too 
deeply  to  be  in  any  danger  of  injury,  removal  of  this 
fat  in  this  manner  will  much  diminish  the  difficulty 
of  the  subsequent  dissection. 

Each  toe  must  now  be  dissected  in  the  following 
manner :  Make  a  deep  midline  incision  the  entire  length 
of  the  plantar  surface  of  each  toe.  By  making  the 
incision  deep  enough  to  expose  the  Sheath  (Theca) 
of  the  Flexor  Tendons,  the  Ligament um  Vaginale  of 
the  Theca  will  be  divided,  and  the  arteries  and  nerves 


THE  SOLE  OF  THE  FOOT  119 

will  be  made  readily  accessible.  Do  not  attempt  to 
separate  the  skin  from  the  underlying  fascia,  but  re- 
flect both  together  laterally  on  both  sides. 

Clean  the  collateral  Digital  Nerves  {nn.  digitalis 
plantares  proprii)  and  trace  them  backwards  to  where 
they  disappear  under  the  digital  sUps  of  the  Plan- 
tar Fascia;  then,  in  the  same  way,  clean  and  trace 
backwards  the  collateral  Digital  Arteries  {aa.  digitales 
plantares  proprii).  The  nerves  are  superficial  to  the 
arteries.  With  scissors,  neatly  trim  away  the  skin- 
flaps  from  along  the  sides  of  the  toes  and  from  the 
web  of  the  toes,  including  all  of  the  dense  fascia  and 
fat. 

It  is  imperative  that  all  five  toes  be  dissected  before 
proceeding  with  the  dissection  of  the  sole. 

On  the  inner  or  mesial  side  of  each  of  the  smaller 
toes  is  a  Lumbrical  Muscle.  All  four  of  these  should 
now  be  cleaned.  Split  open  the  Theca  of  the  Flexor 
Tendons  in  the  midline  of  each  of  the  toes,  thoroughly 
free  the  tendons,  but  do  not  sever  any  of  them.  Divide 
all  of  the  digital  slips  of  the  Plantar  Fascia  {aponeu- 
rosis plantaris)  and  reflect  it  backwards  as  far  as  its 
attachment  to  the  Calcaneum,  but  do  not  detach  it. 

Clean  as  much  as  is  now  exposed  of  the  Plantar 
Digital  Arteries  {aa.  metatarsales  plantares)  and  the 
Plantar  Digital  Nerves  {nn.  digitales  plantares  com- 
munes). This  will  bring  you  to  the  Internal  Plantar 
Artery  {a.  plantaris  medialis)  and  the  Internal  Plantar 
Nerve  {n.  plantaris  medialis),  as  they  emerge  from 
between  the  Abductor  Hallucis  and  the  Flexor  Brevis 
Digitorum.  Also  it  will  lead  to  the  External  Plantar 
Artery  {a.  pUmtaris  lateralis)  and  the  External  Plantar 


120  DISSECTION  METHODS  AND  GUIDES 

Nerve  {n.  plantaris  lateralis),  lying  between  the  Flexor 
Brevis  Digitorum  and  the  Abductor  Minimi  Digiti 
(m.  abductor  digiti  quinti). 

Clean  the  Abductor  Muscle  of  the  Httle  toe,  be- 
ginning at  its  tendon  and  working  backwards  to  its 
origin.  Thoroughly  free  it  from  the  underlying  struc- 
tures and  from  the  Flexor  Brevis  Digitorum.  In  the 
same  way  clean  and  free  the  Abductor  Hallucis  and, 
lastly,  the  Flexor  Brevis  Digitorum.  Lift  up  all  three 
of  these  muscles  and  see  to  it  that  they  are  quite  free 
all  the  way  to  their  origin.  Introduce  a  saw  between 
them  and  the  underlying  structures,  and  then,  by  saw- 
ing horizontally  backwards,  cut  loose  that  part  of  the 
Calcaneum  to  which  they  are  attached. 

Turn  this  flap  downwards  toward  the  toes  and 
clean  its  deep  surface.  Clean  as  much  as  is  now 
readily  accessible  of  the  Plantar  Arteries  and  Nerves 
and  their  branches.  Lift  up  and  free  the  tendon  of  the 
Flexor  Longus  Hallucis,  but  be  careful  not  to  sever 
its  tendinous  communication  with  the  Flexor  Longus 
Digitorum.  Clean  first  the  inner  head  of  the  Flexor 
Accessorius  (w.  quadratus  plantare),  then  its  outer 
head.  Lift  it  up  and  retract  it  inwards  and  clean  the 
Flexor  Brevis  Minimi  Digiti  (m.  flexor  digiti  quinti 
brevis),  working  from  its  insertion  backwards.  Clean 
and  separate  the  two  heads  of  the  Flexor  Brevis 
Hallucis,  working  from  its  two  tendons  backwards. 
Note  the  Sesamoid  Bone  in  each. 

Clean  the  Adductor  Hallucis  {caput  obliquum  m. 
adductoris  hallucis),  lift  it  up,  and  trace  the  deep 
branches  of  the  External  Plantar  Nerve  and  Artery 
as  they  pass  under  its  cover.     Clean  the  Transversus 


FRONT  OF  THIGH,  SUPERFICIAL  DISSECTION  121 

Pedis  Muscle  {caput  transversum  m.  adductor  hallucis) 
as  it  crosses  the  bases  of  the  middle  three  toes.  Divide 
the  common  tendon  of  the  Flexor  Longus  Digitorum 
just  above  its  division  into  the  Digital  Tendons,  but 
below  the  insertion  of  the  Accessorius;  reflect  the 
digital  portion  downwards  and  clean  the  Interosseous 
Muscles. 

FRONT  OF  THIGH,   SUPERFICIAL  DISSECTION 

If  the  back  of  the  thigh  has  already  been  dissected, 
it  will  not  be  necessary  to  make  any  incisions.  Other- 
wise, make  an  incision  from  the  anterior  superior  spine 
of  the  ilium,  down  the  outer  side  of  the  thigh,  to  a 
point  about  a  hand's  breadth  below  the  bend  of  the 
knee.  Make  a  corresponding  incision  down  the  inner 
side  of  the  thigh,  from  the  Spine  of  the  Pubes  to  a 
point  on  the  inner  side  of  the  leg,  a  hand's  breadth 
below  the  bend  of  the  knee.  Do  not  make  any  knife 
incision  along  the  line  of  Poupart's  (Inguinal)  Ligament. 
Begin  at  the  upper  and  outer  part  and  reflect  the  skin 
inwards,  cutting  along  Poupart's  Ligament  with  a  pair 
of  blunt-pointed  scissors. 

If  the  back  part  of  the  thigh  has  already  been 
dissected,  cut  the  skin  with  scissors  along  the  Genito- 
femoral Crease.  Reflect  the  skin  downwards,  to  well 
below  the  knee,  and  trim  it  around  the  leg  with  scis- 
sors. Do  not  encircle  the  leg  with  any  knife  incisions. 
Transverse  knife  incisions  are  unnecessary  as  weU  as 
dangerous. 

Carefully  clean  the  Long  (Internal)  Saphenous  Vein; 
follow  it  upwards  to  where  it  pierces  the  Deep  Fascia 
(fascia  lata).     At  this  point  Uft  it  up  and  carefully 


122  DISSECTION  METHODS  AND  GUIDES 

free  it  from  the  lower  margin  of  the  saphenous  opening 
in  the  fascia  lata,  then  free  it  the  rest  of  the  way 
around.  Begin  at  the  lower  margin  of  the  saphenous 
opening  and  clean  the  inner  margin;  then,  beginning 
at  the  lower  margin,  clean  the  outer  margin.  Note  that 
while  they  are  continuous  at  the  lower  margin,  the 
lateral  margins  of  the  saphenous  opening  are  not  con- 
tinuous above,  but  that  the  outer  margin  overlaps  the 
inner  one. 

Carefully  preserve  the  saphenous  opening.  Do  not 
detach  the  Fascia  Lata  immediately  above  it,  from 
Poupart's  Ligament.  Incise  the  Fascia  Lata  along 
the  anterior  border  of  the  upper  part  of  the  Tensor 
Vaginse  Femoris;  carefully  free  it  from  the  underly- 
ing structures,  working  from  below  upwards,  to  the 
anterior  superior  spine  of  the  ilium.  From  this  point 
detach  it  from  the  outer  third  of  Poupart's  Ligament 
and  reflect  it  downwards  for  an  inch  or  thereabouts. 

Emerging  from  under  Poupart's  Ligament  and  then 
crossing  the  origin  of  the  Sartorius  immediately  below 
the  Anterior  Superior  Spine,  look  for  the  External 
Cutaneus  Branch  of  the  Lumbar  Plexus.  Trace  it 
downwards  and  follow  its  anterior  division  through  its 
canal  in  the  Fascia  Lata,  and  down  the  outer  part  of  the 
front  of  the  thigh.  Just  to  the  outer  side  of  the  Femoral 
Artery,  look  for  the  Anterior  Crural  Nerve;  free  the 
main  trunk  and  trace  its  cutaneous  branches  down- 
wards through  the  Fascia  Lata  and  down  the  front  of 
the  thigh.  The  Middle  Cutaneous  Branch  usually 
pierces  the  Sartorius  Muscle  before  piercing  the  Fascia 
Lata,  so  do  not  mistake  it  for  a  muscular  nerve. 

The  Crural  Branch  of  the  Genitocrural  Nerve  (from 


FRONT  OF  THIGH,  SUPERFICIAL  DISSECTION  123 


Fig.  11. — Genitalia,  Front  of  Thigh,  Front  of  Leg,  and  Dorsum  of 

Foot. 

Continuous  red  lines  indicate  knife  incisions.     The  skin  should  be  cut  along 

the  dotted  red  lines  with  scissors  only. 


124  DISSECTION  METHODS  AND  GUIDES 

Lumbar  Plexus)  enters  the  thigh  in  the  Sheath  of  the 
Femoral  Artery,  which  it  pierces  first  before  piercing 
the  Fascia  Lata.  By  cautiously  separating  the  Fascia 
Lata  from  the  sheath  of  the  femoral  vessels  you  can 
see  the  Genitocrural  Nerve  as  it  bridges  across  to 
pierce  the  Fascia  Lata.  It  is  then  easy  to  trace  it  out. 
Now  that  the  Saphenous  Vein  and  the  Cutaneous 
Nerves  are  safe  from  injury,  remove  all  of  the  over- 
lying fat  and  thoroughly  scrape  and  clean  the  Fascia 
Lata. 

DEEP  DISSECTION   OF  THE  FRONT  AND  INNER    SIDE  OF    THE 

THIGH 

Incise  the  Fascia  Lata  downwards  along  the  anterior 
border  of  the  Tensor  Vaginae  Femoris  and  the  Iliotibial 
Band.  Trim  it  along  Poupart's  Ligament  almost  as 
far  as  the  Saphenous  Opening.  Be  careful  not  to  cut 
the  Superficial  Epigastric  Artery;  then  downwards 
around  the  Saphenous  Opening  and  up  to  Poupart's 
Ligament;  then  reflect  it  downwards  and  remove  it 
entirely  from  the  front  of  the  thigh.  Thoroughly 
free  the  Sartorius  Muscle,  throughout  its  entire  length 
from  origin  to  insertion,  and  thoroughly  clean  it. 
Free  the  Tensor  Vaginae  (fascice)  Femoris  and  the 
Iliotibial  Band  (tractus  iliotibilais)  and  trim  away 
the  Fascia  Lata  from  their  posterior  border.  Free 
the  Rectus  Femoris  Muscle  from  the  underlying 
structures.  Free  the  lower  part  of  the  Adductor 
Magnus  from  the  Vastus  Internus  (Medialis)  in  order 
to  expose  the  roof  of  Hunter's  (Adductor)  Canal. 

Clean  the  Anterior  Crural  (Femoral)  Nerve  and 
trace  out  each  of  its  branches  to  its  termination.     In 


DEEP  DISSECTION  OF  THE  FRONT  OF  THE  THIGH     125 

tracing  the  Saphenous  Nerve,  follow  it  downwards  into 
Hunter's  Canal  (Adductor  Canal) ;  lay  open  the  upper 
part  of  the  roof  of  the  canal,  saving  only  the  part  in 
front  of  the  opening  in  the  Adductor  Magnus;  follow 
the  Patellar  Branch  (ramus  infrapatellaris)  to  where  it 
pierces  the  Sartorius,  and  the  main  trunk  of  the 
Internal  Saphenous  downwards  under  the  Tendon  of  the 
Sartorius.  Be  careful  not  to  injure  the  Anastomotica 
Magna  Artery  (arteria  genu  supremo).  The  other 
branches  of  the  Anterior  Crural  (Femoral)  Nerve 
present  no  difficulties,  but  unless  they  are  all  traced 
out  so  that  they  can  be  retracted  freely,  the  dissection 
of  Scarpa's  Triangle  (Femoral  Trigone)  will  be  very 
difficult. 

Open  the  sheath  of  the  Common  Femoral  Artery, 
split  it  with  scissors,  working  cautiously  upwards  until 
you  encounter  the  Superficial  Epigastric  Artery  branch- 
ing upwards ;  then  trim  the  sheath  around  the  Epigastric 
and  widely  open  it  by  transverse  cuts.  Using  your 
forceps,  free  the  outer  part  of  the  sheath  from  the 
outer  side  of  the  artery,  working  from  above  down- 
wards. In  this  way  it  will  be  possible  to  see  the  col- 
lateral branches  long  before  they  are  in  danger  of  being 
divided.  When  you  encounter  a  branch,  cut  the  sheath 
transversely  to  the  base  of  the  branch  and  trim  it 
away  from  around  it;  continue  stripping  the  sheath 
away  until  you  are  again  obstructed  by  a  branch,  and 
deal  with  it  in  the  manner  given.  When  you  are 
cleaning  an  artery,  always  remove  all  Venae  Comites. 
Never  use  a  knife  in  removing  the  sheath  of  an  artery; 
use  only  forceps,  a  blunt-pointed  probe,  and  blunt- 
pointed  scissors. 


126  DISSECTION  METHODS  AND  GUIDES 

Remove  the  sheath  of  the  Superficial  Femoral  Artery, 
following  it  all  the  way  to  the  opening  in  the  Adductor 
Magnus.  Be  careful  not  to  divide  the  Anastomotica 
Magna  (arteria  genu  supremo),  and  in  Hunter's  (Fem- 
oral) Canal,  be  careful  not  to  tear  the  Femoral  Vein, 
which  usually  is  quite  adherent  there.  Defer  working 
out  the  branches  of  the  Profunda  until  later. 

Trace  out  the  Superficial  Circumflex  Iliac,  Super- 
ficial and  Deep  External  Pudendal  Arteries. 

Free  and  clean  the  Femoral  Vein.  It  will  be  neces- 
sary to  tie  and  cut  off  most  of  its  branches.  It  is  only 
important  to  save  the  Great  Saphenous  and  the 
Femoral  Veins  in  the  thigh.  Flex  the  thigh  in  order 
to  relax  the  anterior  muscles.  Retract  the  Rectus 
Femoris  Muscle  out  of  the  way  and  clean  the  com- 
mencement of  the  Deep  (Profunda)  Femoral  Artery 
and  its  External  (Lateral)  Circumflex  branch.  Clean 
the  direct  head  of  the  Rectus,  retract  the  Tensor 
Vaginae  (fascice)  Femoris  outwards,  clean  the  reflected 
head  of  the  Rectus,  and  remove  the  fat  from  the  front 
of  the  capsule  of  the  hip-joint. 

Free  the  GraciHs  and  Adductor  Longus  and  clean 
them  thoroughly  throughout  their  entire  length.  Re- 
tract the  Adductor  Longus  inwards ;  look  for  the  Obtu- 
rator Nerve  on  the  front  of  the  Adductor  Brevis. 
Clean  the  Obturator  Nerve  and  trace  out  its  anterior 
and  posterior  divisions.  Finish  cleaning  the  Profunda 
Artery,  and  trace  each  of  its  perforating  branches  to 
where  they  pierce  the  Adductor  Magnus. 

Free  the  Pectineus,  Psoas,  and  Iliacus  Muscles 
from  each  other  and  from  the  underlying  structures, 
but  on  no  account  should  any  one  of  them  be  cut. 


FRONT  OF  THE  LEG  AND  DORSUM  OF  FOOT  127 

Clean  the  Internal  (Medial)  Circumflex  Artery,  and 
follow  it  in  between  the  Pectineus  and  Psoas. 

Flex  and  sUghtly  adduct  the  thigh,  lift  up  the  Ad- 
ductor Longus,  and  free  the  Adductor  Brevis. 

Retract  the  Pectineus  outwards;  free  the  upper 
border  of  the  Adductor  Magnus,  expose  the  Obturator 
Externus  Muscle  and  the  Obturator  Artery.  Unless 
these  structures  have  already  been  partly  cleaned  in 
the  dissection  of  the  Gluteal  Region,  it  would  be 
better  to  defer  cleaning  them  until  they  can  be  got  at 
from  behind  as  well  as  from  in  front. 

Trace  out  the  Anastomotica  Magna  {arteria  genu 
supremo).  Finish  cleaning  the  Quadriceps  Femoris, 
but  do  not  try  to  separate  the  Crureus  (vastus  inter- 
medius)  from  the  Vastus  Internus  (medialis). 

FRONT  OF  THE  LEG  AND  DORSUM  OF  FOOT 

First  thoroughly  clean  the  surface  of  the  leg  and 
scrape  away  as  much  of  the  epithelium  as  will  readily 
come  away.  Remove  the  toe-nails  if  they  are  loose, 
and  thoroughly  scrape  away  the  epitheUum  from  the 
plantar  surface  of  the  foot  and  the  toes. 

Neglect  in  this  respect,  will  cause  much  annoyance 
and  delay.  If  the  back  of  the  leg  has  already  been  dis- 
sected, but  the  sole  of  the  foot  has  not,  it  will  only  be 
necessary  to  incise  the  skin  along  each  side  of  the  foot, 
from  the  point  of  the  heel  to  the  plantar  crease  of  the 
toes.  Otherwise,  make  an  incision  down  the  front  of 
the  leg,  following  the  Une  of  the  crest  of  the  tibia  down 
to  the  interval  between  the  great  toe  and  index-toe. 
Do  not  make  any  transverse  knife  incisions  anywhere. 
Remove  the  skin  from  the  front  of  the  leg  and  the 


128  DISSECTION  METHODS  AND  GUIDES 

dorsum  of  the  foot  as  far  down  as  the  bases  of  the  toes, 
at  which  level,  trim  it  away  transversely  with  scissors. 
Incise  the  skin  along  the  midline  of  the  back  of  each 
toe,  reflect  it  laterally  from  each  toe,  and  from  the 
web  between  the  toes  as  far  as  the  plantar  surface;  then 
trim  it  away  neatly  from  the  sides  of  the  toes,  leaving 
only  plantar  skin  on  the  foot  and  toes.  Before  at- 
tempting to  remove  any  of  the  superficial  fat,  the  veins 
and  cutaneous  nerves  should  first  be  worked  out. 
Follow  the  Long  or  Internal  Saphenous  Vein  (v.  saphena 
magna)  downwards  on  to  the  dorsum  of  the  foot.  Its 
collateral  tributaries  will  have  to  be  tied  and  divided. 
Look  for  the  Long  or  Internal  Saphenous  Nerve  (n. 
saphenus)  as  it  emerges  behind  from  between  the 
tendon  of  the  Sartorius  and  the  tendon  of  the 
Gracilis;  follow  its  Posterior  Branch  (n.  cutanei  cruris 
medialis)  as  it  pierces  the  Deep  Fascia  and  becomes 
cutaneous,  and  trace  it  downwards  to  its  termina- 
tion. Look  on  the  front  of  the  Anterior  Annular 
Ligament  (Z,  trans  versum  cruris)  for  one  of  the 
branches  of  the  Musculocutaneous  Nerve  {n.  pero- 
nceus  super ficialis) . 

Pick  up  the  first  one  you  come  across  and  trace  it 
upwards  until  you  encounter  the  main  trunk.  Trace 
the  main  nerve-trunk  upwards  to  where  it  emerges  from 
the  Deep  Fascia,  then  trace  it  and  its  branches  down- 
wards as  far  as  the  middle  phalanges  of  the  toes.  It  is 
highly  important  to  clean  and  thoroughly  free  all  of 
the  branches  of  this  nerve,  otherwise  it  would  be  im- 
possible to  properly  dissect  the  dorsum  of  the  foot. 
Now  that  all  of  the  important  superficial  structures 
have  been  isolated,  clean  away  all  fat.     Divide  the 


FRONT  OF  THE  LEG  AND  DORSUM  OF  FOOT 


129 


Fig.  12. — Front  of  Leg  and  Dorsum  of  the  Foot. 
The  knife  incisions  are  indicated  by  continuous  red  lines.     After  it  has 
been  dissected  away  that   far,  the  skin  should  be  trimmed,  with  scissors, 
along  the  dotted  red  hnes. 


130  DISSECTION  METHODS  AND  GUIDES 

Anterior  Annular  Ligament  (I.  transversum  cruris)  close 
to  its  tibial  attachment,  and  reflect  it  outwards,  open- 
ing its  compartments  as  you  go. 

Pick  up  the  common  tendon  of  the  Extensor  Longus 
Digitorum  (m.  extensor  digitorum  longus),  which  is  the 
third  one  outward  from  the  tibia;  free  each  of  its 
digital  tendons  all  the  way  down  to  the  bases  of  the 
middle  and  distal  phalanges.  By  beginning  at  their 
tendons  and  working  upwards,  free,  in  the  following 
order,  the  Tibialis  Anticus  (m.  tibialis  anterior), 
Extensor  Longus  Digitorum  (m.  extensor  digitorum 
longus),  the  three  Peroneal  Muscles  (mm.  peroncei),  and 
the  Extensor  Proprius  Hallucis  (m.  extensor  hallucis 
longus) . 

Clean  the  Anterior  Tibial  Artery  (a.  tibialis  anterior), 
Anterior  Tibial  Recurrent  (a.  recurrens  tibialis  ante- 
rior). Internal  Malleolar  (a.  malleolaris  anterior  media- 
ns), and  the  External  Malleolar  (a.  malleolaris  anterior 
lateralis)  Arteries. 

Clean  the  Anterior  Tibial  Nerve  (n.  peronceus  pro- 
fundus) and  the  Anterior  Peroneal  Artery  (a.  ramus 
peroncei  perforans) . 

Clean  the  anterior  muscles  of  the  leg  and  remove 
their  sheaths.  Clean  and  thoroughly  free  the  Extensor 
Brevis  Digitorum  Muscle  (m.  extensor  digitorum  brevis) 
so  that  it  can  be  readily  lifted  up  or  retracted.  Clean 
the  Dorsalis  Pedis  Artery,  lift  up  the  Extensor  Brevis 
Digitorum,  and  clean  Tarsal  Artery  (a.  tarsea  lat- 
eralis), the  Metatarsal  Artery  (a.  arcuata),  the  Dorsal 
Interosseous  Arteries  (aa.  metatarsece  dor  sales),  and 
the  outer  branch  of  the  Anterior  Tibial  Nerve  (n.  pero- 
nceus profundus). 


FRONT  OF  THE  LEG  AND  DORSUM  OF  FOOT  131 

Carefully  scrape  away  and  remove  all  overlying 
fat  and  expose  the  Dorsal  Interosseous  Muscles  (mm. 
interossei  dor  sales).  Clean  the  Internal  Lateral  Liga- 
ment il.  calcaneotibiale)  and  the  External  Lateral 
Ligaments  (II.  talofibularia  et  calcaneo fibular e)  of  the 
Ankle-joint  (articulatio  talocruralis) . 


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u 

o'l'Q^ 

jm  ?  9  1931 

i\UG  ii  1  1944 

W0V8»]946' 

NOV  2  9  1946  .,^4^ 

1 

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0  7  ^«^A^ 

.-Hr  1  0  I94j 

1 

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CIv!35       Lie 
LI59 

theny,    D.O 
Dissection 

6051 
methods 

1914 

2,nd  .guides 

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